Class 7

Haryana State Board HBSE 7th Class Science Solutions Chapter 10 Respiration in Organisms Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 10 Respiration in Organisms

HBSE 7th Class Science Respiration in Organisms Textbook Questions and Answers

Question 1.
Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer:
During the race, the athlete has to run very fast. The demand for energy at that time increases, which increase the demand for more supply of oxygen, so, athlete has to breathe faster and deep to inhale more oxygen.

Question 2.
List the similarities and differences between aerobic and anaerobic respiration.
Answer:
Differences between aerobic and anaerobic respiration :

Similarities : (Both aerobic and anaerobic respiration produce energy and give out carbon dioxide.

Question 3.
Why do we often sneeze when we inhale, a lot of dust-laden air?
Answer:
We sneeze to get rid of the unwanted particles like dust etc from our body. It allows only clean and dust free air to enter our body.

Question 4.
Take three test tubes. Fill 3/4th of each tube with water. Label them A, B and C. Keep a snail in test tube A; a water plant in test tube B and in C, keep snail and plant both. Which test tube will have highest concentration of CO₂?
Answer:
There will be highest concentration of CO₂ in tube A.

Question 5.
Tick the correct answer :
(a) In cockroaches air enters the body through :
(i) Lungs
(ii) Gills
(iii) Spiracles
(iv) Skin
Answer:
(iii) Spiracles

(b) During heavy exercise, we get cramps in the legs due to the accumulation of :
(i) carbon dioxide
(ii) lactic acid
(iii) alcohol
(iv) water
Answer:
(ii) lactic acid

(c) Normal range of breathing rate per minute in an average adult person at rest is :
(i) 9-12
(ii) 15-18
(iii) 21-24
(iv) 30-33
Answer:
(ii) 15-18

(d) During exhalation, the ribs :
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Answer:
(ii) move downwards.

Question 6.
Match the items in column I with those in column II.

Answer:
(a) (iii)
(b) (iv)
(c) (i)
(d) (v)
(e) (ii)
(f) (vi).

Question 7.
Make ‘T’ if the statement is true and ‘f if it is false.
(i) During heavy exercise the breathing rate of a person slows down. (T/F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
(iv) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)
Answer:
(i) False
(ii) False
(iii) True
(iv) False
(v) True.

Question 9.
Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction – upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

(i) The air tubes of insects.
(ii) Skeletal structures surrounding chest cavity.
(iii) Muscular floor of chest cavity.
(iv) Tiny pores on the surface of leaf.
(v) Small openings on the sides of the body of an insect.
(vi) The respiratory organs of human beings.
(vii) The openings through which we inhale.
(viii) An anaerobic organism.
(ix) An organism with tracheal system.
Answer:
(i) Trachea
(ii) Ribs
(iii) Diaphragm
(iv) stomata
(v) spiracles
(vi) lungs
(vii) nostrils
(viii) yeast
(ix) ant.

Question 10.
The mountaineers carry oxygen with them because :
(a) At an altitude of more than 5 km there is no air.
(b) The amount of air available to a person is less than that available on the ground.
(c) The temperature of air is higher than that on the ground.
(d) The pressure of air is higher than that on the grow.
Answer:
(b) The amount of air available to a person is less than that available on the ground.

Extended Learning – Activities and Projects

Question 1.
Observe fish in an aquarium. You will find flap like structures on both sides of their heads. These are flaps which cover the gills. These flaps open and close alternately. On the basis of these observations, explain the process of respiration in the fish.
Answer:
Do yourself. Take help your teacher.

Question 2.
Visit a local doctor. Learn about the harmful effects of smoking. You can also collect material on this topic from other sources. You can seek help of your teacher or parents. Find out the percentage of people of your area w ho smoke. If you have a smoker in your family, confront him with the material that you have collected.
Answer:
Do yourself.

Question 3.
Visit a doctor. Find out about artificial respiration. Ask the doctor:
(a) When does a person need artificial respiration?
(b) Does the person need to be kept on artificial respiration temporarily or permanently?
(c) From where can the person get supply of oxygen for artificial respiration?
Answer:
Do yourself.

Question 4.
Measure the breathing rate of the members of your family and some of your friends. Investigate :
(a) If the breathing rate of children is different from that of adults.
(b) If the breathing rate of males is different from that of females.
If there is a difference in any of these cases, try to find the reason.
Answer:
Do yourself.

HBSE 7th Class Science Respiration in Organisms Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is respiration?
Answer:
Respiration is a process of taking oxygen into the cells to break down simple food materials to release energy.

Question 2.
What is breathing?
Answer:
Breathing is inhaling oxygen and exhaling carbon dioxide.

Question 3.
Where does cellular respiration take place?
Answer:
Cellular respiration takes place inside the cells of the body.

Question 4.
What is aerobic respiration?
Answer:
Process of respiration taking place in the presence of oxygen is called aerobic respiration.

Question 5.
What is anaerobic respiration?
Answer:
Process of respiration without the presence of oxygen is called anaerobic respiration.

Question 6.
Does the process of anaerobic respiration take place in human body?
Answer:
Yes, during heavy physical activities, when supply of oxygen is not sufficient, anaerobic respiration takes place in the muscle cells.

Question 7.
What is diaphragm?
Answer:
Diaphragm is a large muscular sheet which forms the floor of the chest cavity.

Question 8.
Name the main respiratory organs in mammals.
Answer:
Lungs are the main respiratory organs in the mammals.

Question 9.
Name the main respiratory organs in insects.
Answer:
Spiracles and tracheae are the main respiratory organs in insects.

Question 10.
Name the respiratory organs in the fish.
Answer:
Gills are the respiratory organs in the fish.

Question 11.
How does earthworm respirate?
Answer:
Earthworm respires through its moist skin.

Question 12.
Where does exchange of gases take place in plants?
Answer:
In plants the exchange of gases takes place through tiny openings called stomata on the leaves.

Short Answer Type Questions

Question 1.
Differentiate between breathing and respiration.
Answer:
Breathing and respiration have following differences:

Question 2.
How does aerobic respiration takes place?
Answer:
In aerobic respiration oxygen is taken into the cells. The food is broken down into simple food materials and energy is released. Carbon dioxide and water is also released.
Gulcose \(\frac{\text { presence of }}{\text { Oxygen }}\) Carbon dioxide + water + energy

Question 3.
What is breathing rate? How is it counted and what is the breathing rate in an adult at the position of rest?
Answer:
Breathing rate is the number of times a person breathes in a minute. To count the breathing rate, we have to count an inhalation and an exhalation as one. Breathing rate in an adult at rest is 15-18 times in a minute.

Question 4.
How is air pushed out during exhalation?
Answer:
During exhalation the ribs move downwards and inwards. The diaphragm moves up and chest cavity gets contracted and air is thrown out.

Question 5.
How do insects breathe?
Answer:
Insects have small openings on the outside of their bodies. These openings are called spiracles, which are connected to the air pipes called tracheae. In tracheae the exchange of gases take place.

Question 6.
How are frogs peculiar in their way of breathing?
Answer:
Frogs breathe differently in water and differently on land. They use their moist skin to breathe in water. They use lungs to breathe on land.

Question 7.
How do plants respirate?
Answer:
Plants also take in oxygen and give out carbon dioxide for respiration. They have small openings called stomata on the surface of there leaves. Exchange of gases take place through these openings.

Long Answer Type Questions

Question 1.
Explain the process of respiration.
Answer:
In respiration, there is a gaseous exchange between the organism and the environment. The process of respiration can be divided in two parts. Breathing and cellular respiration.

Breathing or external respiration: Oxygen is inhaled and Carbon dioxide is exhaled during breathing. This process takes place out side the cells and, thus is called external breathing.

Cellular respiration or internal respiration : This is a biochemical process which takes place inside the cells of the body. In this process food i.e. glucose is broken into simpler forms. Energy is released during this process which is used by body to perform various functions. Carbon dioxide and water is also released. The Carbon dioxide is expelled out during breathing.
Food + Oxygen → Carbon dioxide + Water + Energy.

Question 2.
Explain the process of respiration in plants.
Answer:
In plants the process of respiration leads to the release of energy. It is a cellular process in which molecules of glucose break down in the presence of oxygen to release energy along with water and carbon dioxide. Exchange of gases take place through small openings on the surface of the leaves. These are called stomata. Lower plants lack the organs of breathing. In such plants gaseous exchange occurs due to simple process of diffusion. The rate of exchange of gases in plants is not as fast as in animals.

Respiration in Organisms Class 7 HBSE Notes

• Respiration is a process of taking oxygen into the cells in order to break down simple food materials to release energy and eliminate waste products.
• Breathing is inhaling oxygen and exhaling carbon dioxide.
• Breathing takes place out side the cells.
• Cellular respiration takes place inside the cells.
• Inside the Cells the food is broken into water and carbon dioxide. This is called cellular respiration. This process releases a lot of energy.
• When the process of respiration takes place in the presence of oxygen, it is called aerobic respiration.
• When the process of respiration takes place in the absence of oxygen, it is called anaerobic respiration.
• Human beings have a fully developed respiratory system.
• Nostrils inhale oxygen, which reaches the lungs through the nasal cavity.
• Lungs are organs, where the exchange of gases takes place. Carbon dioxide is expelled out and oxygen is consumed for cellular respiration.
• Smaller animals like cockroaches have structures called spiracles, for breathing. Earthworms breathe through their skin and fish have gills for respiration.
• In both plants and animals, mitochondria is the site of respiration.

Haryana State Board HBSE 7th Class Science Solutions Chapter 9 Soil Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 9 Soil

HBSE 7th Class Science Soil Textbook Questions and Answers

Tick the most suitable answer in questions 1 and 2.

Question 1.
In addition to the rock particles, the soil contains:
(i) air and water,
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants.
Answer:
(iii) minerals, organic matter, air and water.

Question 2.
The water holding capacity is the highest in:
(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam
Answer:
(iii) loamy soil.

Question 3.
Match the items in column I with those in column II:

Answer:

Question 4.
Explain how soil is formed.
Answer:
Soil has been formed from parent rock material over millions of years. The process by which soil formation takes place is called weathering. Weathering is a very slow and gradual process during which parent rock material breaks down into fine particles.

The agents which bring about weathering are many. These are described below:
1. Temperature changes:
Rocks expand when heated and contract when cooled. The hot sun causes the surface layers of rocks to expand more than the layers deeper down. These changes cause the rock surface to break apart.

2. Frost:
Rainwater may become trapped in small crevices of the parent rock. In winter, this water freezes to ice. The ice expands producing a lateral pressure, causing the crevices in the rocks to further open up.

3. Water:
Continual movement of rain and river water, in liquid form, causes breaking down of rock particles into finer particles through their abrasive effect.

4. Wind:
Wind blowing across a rock surface also has a abrasive effect on the rocks. Minute rock particles are carried away by the blowing wind and deposited elsewhere.

Question 5.
How is clayey soil useful for crops?
Answer:
Clayey soils are very useful for crops, because these soils:
(i) contain humus, providing fertility to the soil
(ii) hold sufficient water due to the presence of smaller particles, and
(iii) contain enough air due to the presence of some large particles alsy.

Question 6.
List the differences between clayey soil and sandy soil.
Answer:
Clayey soil:
Clayey soil contains more than 50% of clay particles. Since the clay particles are very small in size, they are very tightly packed and do not allow water to drain out easily. It is poorly aerated because the tightly bound clay particles leave little space in between to trap air. Clayey soil is very sticky and thus tilling the soil is very difficult. However, it is rich in minerals which makes it suitable for plant growth. Due to the great binding capacity of its particles, clayey soil is used for making toys and pots.

Sandy soil:
Sandy soil contains about 60% of sand particles with small amounts of silt and clay. It is very porous and its water holding capacity is very low as all the water easily runs down through the large pores. This type of soil is, therefore, not good for the growth of plants. It is found mainly in the deserts.

Question 7.
Sketch the cross section of soil and label the various layers.
Answer:
Soil profile

Question 8.
Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Answer:
Formula: Percolation rate
\((\mathrm{mL} / \mathrm{min})=\frac{\text { amount of water }}{\text { percolation time }(\mathrm{min})}\)
= \(\frac{200 \mathrm{~mL}}{40 \mathrm{~min}}\)
= 5 mL /min.

Question 9.
Explain how soil erosion could be prevented.
Answer:
Prevention of soil erosion can be brought about by controlling the factors which cause soil erosion. The methods would, thus, be as follows:
1. Deforestation should be stopped. Rather, trees should be planted (afforestation). Afforestation should be undertaken not only in areas already cut, but additional areas should be brought under plantation.

2. To reduce the effect of strong winds in the fields, the boundaries of the fields should be planted with trees in two to three rows.

3. To maintain the soil in its natural condition, it is advisable to grow different crops. Crops rotation, as it is called, helps to maintain the fertility of the soil. The water-holding capacity of the soil is also maintained by this method.

4. Proper drainage and irrigation arrangements should be made in the fields.

5. On the sloping areas in hills, strip cropping should be practised, thereby reducing the steepness of the slopes and checking soil erosion.

Question 10.
Solve the following crossword puzzle with the clues given:

Across:
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.

Down:
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
Answer:

Extended Learning – Activities And Projects

Question 1.
Boojho would like to know the difference between raw and baked soil? Investigate how the soil from which matkas are made is different from the soil used to make status.
Answer:
Do yourself. Take help your teacher.

Question 2.
Paheli is worried. She could see a brick kiln from her house. Bricks were being made there. There was so much smoke coming out of the kiln. She was told that the best quality of clay is required for making pottery, statues and bricks. She has seen truck loads of bricks being taken away for construction of buildings. At this rate, she fears, no soil will be left. Are her fears justified? Discuss this problem with your parents, teachers and other experts of your area and prepare a report.
Answer:
Do yourself.

Question 3.
Try to find out the moisture content of a soil sample. One method is given here.
Activity: Take lOOg soil. (Take help from any shopkeepers to weigh the soil). Place it on a newspaper in the sun and allow it to dry for two hours. This activity is best done in the afternoon. Take care that the soil does not spill outside the newspaper. After drying it, weigh the soil again. The difference in the weight of the soil before and after drying gives you the amount of moisture contained in 100 g of soil. This is called the percentage moisture content.
Suppose your sample of soil loses 10 g on drying. Then
Percent of moisture in soil
= \(\frac{\text { wt. of moisture }(\mathrm{g})}{\text { Original wt. of soil sample }(\mathrm{g})} \times 100\)
In this example
Percent of moisture in soil
= \(\frac{10 \times 100}{100}=10 \%\)
Answer:
Do yourself.

HBSE 7th Class Science Soil Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Define soil.
Answer:
Soil is uppermost layer of earth’s crust, in which plants grow.

Question 2.
Define weathering.
Answer:
Soil is formed from the parent rock material by a very slow and gradual process called weathering.

Question 3.
What is humus?
Answer:The rotting dead matter in the soil is called humus.

Question 4.
Where do plants grow?
Answer:
Plants grow in the soil.

Question 5.
Where does food that helps to sustain and grow, come from?
Answer:
Plants.

Question 6.
How old is our earth?
Answer:
Our earth came into existence about 4.5 billion years ago.

Question 7.
Name the part of the environment which supports life.
Answer:
1. Lithosphire
2. Hydrosphere
3. Atmosphere.

Question 8.
Give one term for the following,
“Removal of top soil by air and water.”
Answer:
Soil erosion,

Question 9.
What do you understand by the term soil conservation?
Answer:
Prevention of soil erosion is called soil conservation.

Question 10.
What is soil pollution?
Answer:
When the structure and properties of the soil are changed by adding unwanted and harmful substances, it is called as soil pollution.

Question 11.
Name two soil pollutions.
Answer:
(i) Insecticides and herbicides
(ii) Industrial wastes like plastic, chemicals, flyash, leather etc.

Question 12.
How soil erosion takes place?
Answer:
When the over grazing or cutting of trees take place the top soil becomes soft and loose which is easily blown by wind and water.

Question 13.
How is soil formed?
Answer:
Soil is formed by cracking of rocks due to contraction and expansion by cooling and heating effect.

Question 14.
What is mineral?
Answer:
Minerals are the non-renewable natural resources.

Question 15.
Name four animals that live in the soil.
Answer:
Bacteria, Earthworm, Snakes, Rats, Ants.

Question 16.
What do you understand by deforestation?
Answer:
When the trees of the forest are cleared to convert the forest land into formland is called deforestation.

Question 17.
State two major problems caused by excessive deforestation.
Answer:
(i) Due to excessive deforestation there is less rain.
(ii) Soil erosion takes place.

Question 18.
Name the materials present in fertile soil.
Answer:
Fertile soil contains nitrates, phosphates, water soluble salts and carbonic acids.

Question 19.
What is crumb?
Answer:
The main skeleton of a fertile soil is called crumb.

Question 20.
What, is the function of air in soil?
Answer:
(i) Air helps, 1:he plants present in the soil in respiration.
(ii) It helps in making soil soft and light in weight.

Question 21.
Which soil horizon is rich in humus?
Answer:
The uppermost layer is called the A- horizon is rich in humus.

Question 22.
Which type of soil is best suited for growth of plants?
Answer:
Loamy soil.

Question 23.
Name the different types of particles present in soil.
Answer:
Soil consists of soil particles, humus (organic matter), water, air and living organisms.

Question 24.
What is strip, cropping?
Answer:
Strip cropping means the planting of crops in rows or strips to check flow of water.

Question 25.
What are loams?
Answer:
Soils having mixtures of different sized particles are called loams or loam soils.

Short Answer Type Questions

Question 1.
What are the components of soil?
Answer:
Some of the main components of soil are as follows:
(i) Humus
(ii) Minerals
(iii) Water
(iv) Air and
(v) Micro organisms 7 bacteria, fungi, insects, larvae and many other organisms.

Question 2.
Write the importance of Humus.
Answer:
Humus is very important for the proper growth of the plants. It helps in growing plants in the following ways:
(i) It makes the soil fertile.
(ii) It allows the roots of plants to penetrate in the soil easily.
(iii) Water and air can pass into it easily,
(iv) It retains water for a longer period.
(v) It binds the soil particles.

Question 3.
What is meant by term wehtherifig?
Answer:
The cooling and heating of rocks cause cracking. They bring about further breaking. This process of breaking the parent rock into fine particles is called weathering.

Question 4.
Describe the harmful effects of deforestation.
Answer:
Deforestation causes the following harmful effects:
(i) Soil erosion will take place.
(ii) There will be draught due to which famine will occur. .
(iii) There will be less rain.
(iv) There will be excess amount of CO, due to which Green House effect will take place. It may cause flood in-the rivers.

Question 5.
Why biosphere supports life?
Answer:
Biosphere has all those requirements such as air, water, minerals, sunlight etc. which are essential for the survival of living things.

Question 6.
What are natural resources?
Answer:
Natural resources are those which are provided by nature to support life. Such as water, air, minerals, sunlight and various life forms.

Question 7.
What is soil erosion?
Answer:
The top soil being soft and light is carried away easily by wind and water, the natural agents. This process of removal of soil is called soil erosion.

Question 8.
Distinguish between residual and transported soils.
Answer:
Residual soils are those in which the whole process of soil formation, i.e., weathering and development of soil profile occurs at the same place. In these soils, the soil is formed at the place where the parent rock is present.

Transported soils are those where the v weathered soil particles are taken away to other places. This is done by several agents.

Question 9.
State any four major advantages of forests.
Answer:
Forest is a natural renewable resource which is advantageous in the following ways:
(i) It creates a suitable environment for rain.
(ii) It helps in controlling the soil erosion.
(iii) It absorbs excess rain water as subsoil water.
(iv) It provides the home to variety of animals.

Question 10.
What is the importance of soil organisms?
Answer:
A number of organisms such as earthworms, bacteria, fungi and round- worms are found in the soil.
Soil organisms are important because of various uses:
1. As you know, earthworms burrow the soil, swallow it and make it loose and soft.
2. Micro-organisms cause the decomposition’ of dead plants and animals, and release the minerals back of the soil. The minerals can again be absorbed by the plant roots. Mineral cycling goes on in this manner.
3. Some bacteria are able to fix nitrogen in association with roots of legume plants like pea and gram.

Long Answer Type Questions

Question 1.
How is soil important to us? Explain.
Answer:
Our mother Earth is blessed with immense land resource. It is valuable to man for food production. It is also a basic part of wildlife habitats and recreational resources. Various soil organisms like earthworms, bacteria, insects and mammals use this as a natural habitat. Plants obtain water and minerals through this land resource. Plant sources of many medicinal drugs exist here. Wood fibres, fruits, rubber, oils, dyes and various other economic products which the man uses, are all dependent on this land. The very existence of mankind is greatly influenced by this land resource.

Question 2.
Describe the factors which cause soil erosion.
Answer:
Soil erosion is the removal of topsoil. This is brought about by wind and water or rain. There are several factors which allow water and wind to cause soil erosion. Some of these factors are:
(i) Deforestation:
Cutting down of trees and excessive farming are practices that destroy vegetation and expose land to the action of wind and water. Water runs off the soil surface with great speed and carries the soil particles into rivers which get chocked with silt resulting in floods. This problem assumes alarming proportions on hills.

(ii) Overgrazing:
Overgrazing by animals also destroys vegetation making land barren. The top soil on barren land can then be eroded by water and wind.

(iii) Poor methods of farming:
Tilling or ploughing loosens the soil which can then be easily eroded by wind and water. Due to excessive farming the layer of humus gets depleted and water holding capacity of the soil also reduces. The topsoil thus dries up and can be carried away by wind and water.

(iv) Forest fires, too, lead to soil erosion. After fire, the soil is exposed to two main factors causing erosion, namely wind and water.

Question 3.
Write short notes on the importance of the following:
(а) Soil, (b) Forests, (c) Soil organisms, (d) Overgrazing, (e) Earthworms.
Answer:
(a) Soil:
(i) Soil provides shelter to several micro-organism and some macro- organisms.
(ii) All the plants grow in it.
(iii) It acts as store-house of minerals.
(iv) It acts as raw material for building bricks, mortar, pottery, pulp for paper industry is. obtained from plants grown in the soil.
(v) It acts as water storage.
(vi) It provides employment.

(b) Forests: Forests are very useful to man-kind in the following ways:
(i) It maintains the balance of gases in the atmosphere.
(ii) It causes rain.
(iii) It provides the shelter to the wild animals.
(iv) It provides the valuable things like timber, honey, bee wax, lac, medicines.

(c) Soil Organisms:
Various micro organisms live in the soil which make the soil porous, soft and airy. They make soil fertile. They convfert manure into simple form which can be used by plants of the forest.

(d) Overgrazing:
When the cattle , eat grass of l^rge area, it is called as overgrazing. This process makes the soil plain which can be used for industrialisation and urbanisation.

(e) Earthworm:
Earthworms are the friends of the farmer. They eat dead organicv substances along with the soil and convert them into simple soluble forms which make the soil fertile and soft.

Question 4.
Describe the composition of soil.
Answer:
Composition of soil varies from place to place. It depends on the type of rock from which it is formed. However, all soils contain the following components:
(i) Rock particles: Tiny particles of soil derived from the parent rock.
(ii) Humus: Humus consists of decaying remains of plants and animals.
(iii) Living organisms: Soil contains a large number of micro-organisms like bacteria, algae, fungi and protozoa. Many small animals like insects, earthworms, spiders, scorpions, centipedes and millipedes are found in the soil. Burrowing animals like rats, moles, rabbits and guinea pigs make tunnels in the soil.
(iv) Water: Water is present in pores between soil particles and helps the plants in their growth.
(v) Air: Air is also present in the soil pores and is essential for the survival of living organisms present in the soil.

Question 5.
What is soil pollution? What are the major sources of soil pollution?
Answer:
Any substance that adversely affects the, productivity of soil is called a soil pollutant. Contamination of soil with pollutants like insecticides, artificial fertilizers and industrial wastes is called soil pollution. The major sources of soil pollution are:
(i) Pollutants like acids washed off from the atmosphere (acid rain).
(ii) Pesticides and herbicides sprayed in fields.
(iii) Excessive use of artificial fertilizers.
(iv) Solid wastes like garbage, trash, ash, building material, plastic bottles and cans.

Soil Class 7 HBSE Notes

1. Soil is the uppermost layer of earth’s crust, in which plants grow.
2. Soil is formed from the parent rock material by a very slow and gradual process called weathering. A number of agents temperature changes, frost, water, wind and living organisms – are involved in the weathering of rocks.
3. Six types of soil are mainly found in India – Red soil, black soil, alluvial soil, desert soil, mountain soil and laterite soil. Humus content is maximum in mountain soil. Black soils are rich for growing cotton and sugarcane while alluvial soil is suitable for wheat and rice.

4. There are three main layers or horizons in the soil profile – A-horizon (top soil), B horizon (subsoil) and C-horizon (parent rock).
5. Soil consists of soil particles, humus (organic matter), water, air and living organisms.
6. Soil particles, depending on size, consist of clay (below 0.002 mm), silt (0.002 to 0.02 mm), sand (0.02 to 2.0 mm) and gravel (above 2.0 mm).
7. A soil containing a mixture of sand, silt and clay is called a loamy soil. It is the best soil for plant growth.
8. Soil is an important natural resource. It provides us food, clothing, shelter, medicines,
rubber, dyes and a number of other useful products. Besides man, it provides shelter to wildlife and different soil organisms.
9. Wind and rain bring about loss of the top soil (soil erosion). Deforestation, over grazing and poor farming methods have accelerated the process of soil erosion.
10. Prevention of soil erosion (soil conservation) can be brought about by growing plants (afforestation), crop rotation, prevention of overgrazing maintaining proper drainage, and growing crops in rows or strips in the hills (strip-cropping).

Haryana State Board HBSE 7th Class Science Solutions Chapter 8 Winds, Storms and Cyclones Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 8 Winds, Storms and Cyclones

HBSE 7th Class Science Winds, Storms and Cyclones Textbook Questions and Answers

Question 1.
Fill the missing word in the blank spaces in the following statements:
(a) Wind is …………… air.
(b) Winds are generated due to …………… heating on the earth.
(c) Near the earth’s surface air rises up whereas …………… air comes down.
(d) Air moves from a region of …………… pressure to a region of …………… pressure.
Answer:
(a) moving
(b) uneven
(c) warm, cooler
(d) high, low.

Question 2.
Suggest two methods to find out wind direction at a given place.
Answer:
(i) Take a piece of a paper in your hand. Let it fall from your hand. It will blow in the direction in which wind is blowing.
(ii) You can use a wind vane (a device helps us to make accurate measurements of wind direction) to find out the direction of wind.

Question 3.
State two experiences that made you think that air exerts pressure (other than those given in the text).
Answer:
(i) Balloons and balls can be used only when they are inflated with air.
(ii) Compressed air is used in the brake system for stopping trains.

Question 4.
You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Answer:
No. A house which has no ventilators is not a healthy house to live in. The air circulation is not there in such a house and hence it has no fresh air.

Question 5.
Explain why holes are made in hanging banners and hoardings.
Answer:
Air exerts pressure. It is due to this pressure banners and hoardings flutter when the wind is blowing. Holes are made in the banners and hoardings as wind pass through that holes and they does not become loose and fall down.

Question 6.
How will you help your neighbours in case cyclone approaches your village/town?
Answer:
(i) A cyclone forecast and warning service.
(ii) Rapid communication of warnings to the Government agencies, the ports, fishermen, ships and to the general public.
(iii) Construction of cyclone shelters in the cyclone prone areas, and Administrative arrangements for moving people fast to safer places.

Question 7.
What planning is required in advance to deal with the situation created by a cylone?
Answer:
In order to deal with cyclone, it is important to follow the following points:
(i) listening carefully to warnings being transmitted on TV and radio.
(ii) moving to safer places or taking adequate steps to ensure safety at home.
(iii) keeping an emergency kit ready.
(iv) storing food in water-proof bags.
(v) not venturing into sea.
(vi) keeping all the emergency numbers handy.

Question 8.
Which one of the following place is unlikely to be affected by a cyclone?
(i) Chennai
(ii) Mangalore
(iii) Amritsar
(iv) Puri
Answer:
(iv) Puri.

Question 9.
Which of the statements given below is correct?
(i) In winter the winds flow from the land to the ocean.
(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high pressure system with very high speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.
Answer:
(i) In winter the winds flow from the land to the ocean.

Extended Learning – Activities And Projects

Question 1.
You can perform the Activity 8.5. in the chapter at home slight differently at home. Use two plastic bottles of the same size. Stretch one balloon on the neck of each bottle. Keep one bottle in the sun and the other in the shade. Record your observations. Compare these observations and the result with those of Activity 8.5.
Answer:
Do yourself.

Question 2.
You can make your own anemometer. Collect the following items:
4 small paper cups (used ice-cream cups), 2 strips of cardboard (20cm long and 2cm wide), gum, stapler, a sketch pen and a sharpened pencil with eraser at one end.
Take a scale; draw crosses on the cardboard strips as shown in the Fig. 8.4. This will give you the centres of the strips.

Finding centre of the strips

A model of an anemometer
Fix the strips at the centre, putting one over the other so that they make a plus (+) sign. Now fix the cups at the ends of the strips. Colour the outer surface of one cup with a marker or a sketch pen. All the 4 cups should face in the same direction.

Push a pin through the center of the strips and attach the strips and the cups to the eraser of the pencil. Check that the strips rotate freely when you blow on the cups. Your anemometer is ready. Counting the number of rotations per minute will give you an estimate of the speed of the wind. To observe the changes in the wind speed, use it at different places and different times of the day.

If you do not have a pencil with attached eraser you can use the tip of a ball pen. The only condition is that the strips should rotate freely.
Remember that this anemometer will indicate only speed changes. It will not give you the actual wind speed.
Answer:
Do yourself.

Question 3.
Collect articles and photographs from newspapers and magazines about storms and cyclones. Make a story on the basis of what you learnt in this Chapter and the matter collected by you.
Answer:
Do yourself.

Question 4.
Suppose you are a member of a committee, which is responsible for creating development plan of a coastal state. Prepare a short speech indicating the measures to be taken to reduce the suffering of the people caused by cyclones.
Answer:
Do yourself.

Question 5.
Interview eyewitness to collect the actual experience of people affected by a cyclone.
Answer:
Do yourself.

Question 6.
Take an aluminium tube about 15 cm long and 1 to 1.5 cm in diameter. Cut slice of a medium sized potato about 2 cm thick. Insert the tube in the slice, press it, and rotate it 2-3 times. Remove the tube. You will find a piece of potato fixed in the tube like a piston head.

Repeat the same process with the other end of the tube. Now you have the tube with both ends closed by potato pieces with an air column in between.

Take a pencil with one end unsharpened. Place this end at one of the pieces of potato. Press it suddenly to push the potato piece in the tube. Observe what happens. The activity shows rather dramatically how increased air pressure can push things.
Caution: When you perform this activity, make sure that nobody is standing in front of i e tube.
Answer:
Do yourself.

HBSE 7th Class Science Winds, Storms and Cyclones Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is a wind?
Answer:
The moving air is called wind.

Question 2.
Define the term ‘cycle’.
Answer:
It is an event or phenomenon which repeats itself after sometime.

Question 3.
Define term ‘evaporation’.
Answer:
The process of changing water from its liquid form to its vapour is known as evaporation.

Question 4.
Is evaporation a slow process or fast process?
Answer:
Evaporation is a slow process.

Question 5.
Name two processes through which water vapour add continuously into the air.
Answer:
The two processes are:
(i) Evaporation
(ii) Condensation.

Question 6.
Define condensation.
Answer:
The process of conversion of water vapours into liquid form of water is called condensation.

Question 7.
Define water cycle.
Answer:
The water in its vapour form goes into air by evaporation and transpiration forms cloud and, then comes back to the surface of the earth through the process of condensation and precipitation. This process is called ‘water cycle’.

Question 8.
At what speed wind becomes (i) gentle breeze, (ii) storm?
Answer:
When the wind blows gently, it is called a breeze. But, when it blows very fast it causes storm.

Question 9.
What is sea breeze?
Answer:
In coastal areas, during the day, the cool air blows from sea towards the land called sea breeze.

Question 10.
What is land breeze?
Answer:
In coastal areas, during the night, the cool air blows from land to sea called the land breeze.

Question 11.
What is tornadoes?
Answer:
In our country tornadoes are not very frequent. A tornado is a dark funnel shaped cloud that reaches from the sky to the ground.

Question 12.
What is ‘hurricane’?
Answer:
The ‘hurricane’ is the term used for storm in America and West Indies.

Question 13.
What is the eye of hurricane?
Answer:
The region of chimney like low pressure around which warm water vapour spirals is called the eye of hurricane.

Question 14.
What is Beaufort Scale?
Answer:
The number and name of.a wind is determined by the speed at which it flows on an internationally accepted scale, called Beaufort scale.

Question 15.
Name two properties of air.
Answer:
(i) Air occupies space
(ii) It has mass.

Question 16.
Write two importances of air in agriculture.
Answer:
(i) Air helps rotate wind-mill which is used to draw water from tube-wells.
(ii) Air helps in dispersion of seeds and pollen grains of flowers of several plants.

Question 17.
How are high building protected from lightning?
Answer:
High buildings are protected from lightning by fixing lightning conductor on the building.

Question 18.
What is the cause of atmospheric electricity?
Answer:
Atmospheric electricity is due to ionisation of air by the ultraviolet rays of sunlight.

Question 19.
Is our body a conductor?
Answer:
Yes, our body is a good conductor of electricity.

Question 20.
What damage can lightning do?
Answer:
Lightning damage the high buildings and the trees on which it strikes. The buildings and trees can be set on fire by lightning. It can do a high loss of life and property.

Question 21.
Why do chimneys made of steel not require lightning conductor?
Answer:
Steel is a good conductor of electricity. Due to this reason steel chimneys do not require lightning conductor. They themselves pass the discharge to the earth.

Question 22.
Why is it advised not to take shelter under a tree during lightning?
Answer:
We should not stand under a tree during lightning, due to the danger of the lightening, because it can destroy the trees and can set it on fire.

Question 23.
Which gas is produced in air during lightning that absorbs ultraviolet radiation present in sunlight?
Answer:
During lightning ozone (oz) gas is produced due to higher temperature which absorbs ultraviolet radiation. It is dangerous for the living being.

Question 24.
Name the arrangement used for the protection of buildings against damage from lightning.
Answer:
To protect buildings from damage by lightning, a good lightning conductor is used. This is done by installing a lightning conductor on the buildings.

Short Answer Type Questions

Question 1.
How is rain caused?
Answer:
Water, on land, is present in different sources, e.g., sea, river, pond, lake, etc. The water from all these sources change into vapour form due to sun’s heat and goes up into the air. This change of water into vapour form is called evaporation. The water vapour, when reaches high up in the air, cools down and forms clouds. This cooling down of water vapour to form clouds is called condensation. On cooling, the water vapour changes to water droplets. These group together farm clouds. When the droplets become very heavy they fall down as rain.

Question 2.
What is water cycle? What does it indicate?
Answer:
Evaporation of water from oceans, ponds, rivers, lakes and from roads and streets to form cloud by condensation at higher altitude. When clouds rain, the rain water flows into the seas and oceans through rivers and streams. Some water percolates into the soil to form underground water. It comes again out in the form of spring and well. This is called water cycle.

Because of water cycle, the amount of water on the earth remains more or less the same. The water cycle also indicates that all the water in world is on the move all the time.

Question 3.
How does water cycle help in maintaining global climate?
Answer:
Water cycle plays an important role in the world climate. Oceans absorb vast quantities of heat and help in global warming. By absorbing heat water evaporates and on condensation releases heat. This absorption and releasing of heat in the form of energy drives weather pattern in the short term and regulate the climate for long time.

Question 4.
How is storm caused?
Answer:
When the wind blows gently, it is called a breeze. But, when it blows very fast it causes storm. Storm may be defined as something taking place in the weather of a violent nature. At sea, a storm may be a strong wind or gale. On land, a storm usually means a weather situation marked by heavy rain and often with strong winds, lightning and thunder.

Question 5.
How a thunderstorm becomes a cyclone?
Answer:
Water requires heat when it changes from liquid to vapour state. Before cloud formation water takes up heat from the atmosphere to change into vapour. When water vapour changes back to liquid form as raindrops, this heat is released to the atmosphere. The heat released to the atmosphere warms the air around. The air tends to rise and causes a drop in pressure. More air rushes to the centre of the storm. This cycle is repeated. The chain of events ends with the formation of a very low pressure system with very high speed winds revolving around it. It is this weather condition that we call a cyclone.

Question 6.
How is lightning useful in nature?
Answer:
Lightning is useful in nature because during lightning intense heat and high temperature are produced. As a result, nitrogen combines with oxygen to form its oxides. These oxides of nitrogen further get dissolved in water to form a dilute solution of nitric acid that comes to the ground with rain. This is how nature provides nitrogenous compounds to plants that are important for their growth.

Question 7.
How is ozone layer useful for us?
Answer:
During lightning, a part of oxygen gets converted to ozone. Ozone provides protection against harmful ultraviolet radiations of the sun that cannot reach the earth’s surface.

Question 8.
What are the precautions to be taken against a storm is accompanied by lighting?
Answer:
If a storm is accompanied by lightning, we must take the following precautions:
(i) Do not take shelter under an isolated tree. If you are in a forest take shelter under a small tree. Do not lie on the ground.
(ii) Do not take shelter under an umbrella with a metallic end.
(iii) Do not sit near a window. Open garages, storage sheds, metal sheds are not safe places to take shelter.
(iv) A car or a bus is a safe place to take shelter.
(v) It you are in water, get out and go inside a building.

Question 9.
Why is it advisable to switch off TV sets during lightning?
Answer:
Lightning in the sky also effects radio and TV transmission in our radio and TV sets during lightning and thunder is due to this reason. TV antina and dish antina has fixed on tall buildings are especially prove to lightning strikes. So it is advisable to stop our TV set during lightning to save them from damage.

Question 10.
What is a lightning conductor? Why is it fixed on the top of high tall buildings?
Answer:
A lightning conductor is a long flat thick strips of copper with sharp point or spikes. The lower end of it is connected to copper plate deep into the earth. It is fixed on the top of the building because the thundering electricity comes in the contact first and the building will not be damaged.

Question 11.
How are lightning and thunder caused?
Answer:
When two oppositively charged clouds are near each other, the air between them becomes good conductor because charges begin, to move in air very speedily. The presence of electric charges in very large quantities in the air causes to appear as steaks of lightning and thunder.

Question 12.
When do we say that lightning has struck on the earth?
Answer:
Sometimes the direction of the wind changes; then the clouds move and the charges in the clouds are discharged into the earth when it happens, then it is said that lightning has struck on the earth.

Question 13.
Why should we not stand under a tree during a thunderstorm?
Answer:
We should not stand under a tree during a thunderstorm due to the danger of the lightning because it can destroy the tree, and can set it on fire.

Question 14.
What are tornadoes?
Answer:
In our country tornadoes are not very frequent. A tornado is a dark funnel shaped cloud that reaches from the sky to the ground. Most of the tornadoes are weak. A violent tornado can travel at speeds of about 300 km/h. Tornadoes may form within cyclones.

Question 15.
Write short note on ‘lightning conductor’.
Answer:
A lightning conductor is made up of long, thick metal rod having sharp spikes at its upper end. The spikes pointing towards the sky are fixed at the highest points of the building. The lower end of the metal rod is connected to a large copper or aluminium plate which is hurried deep inside the earth which is called earthing.

When a highly charged cloud passes over a tall building, it induces an opposite charge on the spikes. This charge quickly flows to the earth through the copper rod. Hence, the lightning discharge is prevented and the building is saved from damage.

Question 16.
Explain how lightning takes place?
Answer:
Normally air is a bad conductor of electricity. However, when two clouds having huge amount of positive and negative state charges approach each other, the air becomes a good conductor of electricity.

Thus the electrons from the negatively charged cloud push their way through air so as to reach the positively charged cloud. In doing so the air gets white hot and hence a dazzling bluish white streak of light is formed which is called lightning.

Question 17.
What precautions should be taken to provide protection against lightning?
Answer:
Precautions should be taken to provide protection against lightning:
Answer:
(i) Lightning conductor provides us a simple means to protect against damage due to lightning property and life.
(ii) When lightning strikes, it provide a path to the entire charge through it to the earth.
(iii) We should not stand under, I tree during a thunderstorms due to the air of lightning, because it destroys trees set it on fire.
(iv) Lightning conductor should be installed on large buildings and tall chimneys of factories.

Long Answer Type Questions

Question 1.
Describe water cycle in nature.
Answer:
Water constantly moves from the earth to the air and back again.
The constant circulation of water is known as the water cycle.

The water in seas, rivers, lakes, ponds or streams evaporates because of the heat of the sun.

Plants also give out large amounts of water from their leaves. The water vapour rises up. The air higher up in the atmosphere is cooler. This cools the water vapour and it condenses to form tiny drops of water on dust particles. These drops of water together form clouds. As the clouds get cooled further, the water drops become bigger and heavier. When they become too heavy, they fall to the earth as rain. The rain water enters the seas, rivers, lakes, ponds and streams and then evaporates again. Thus the water cycle in nature goes on.

Question 2.
Explain destructions caused by cyclones.
Answer:
Cyclones can be very destructive. Strong winds push water towards the shore even ;f the storm is hundreds of kilometres away. These are the first indications of an approaching cyclone. The water waves produced by the wind are so powerful that a person cannot overcome them.

The low pressure in the eye lifts water surface in the centre. The rising water may be as high as 3-12 metres. It appears like a water wall moving towards the shore. As a result the seawater enters the low-lying coastal areas, causing severe loss of life and property. It also reduces the fertility of the soil.

Continuous heavy rainfall may further worsen the flood situation. High speed winds accompanying a Cyclone can damage houses, telephones and other communication systems, trees, etc; causing tremendous loss of life and property.

Question 3.
What is lightning? How does ligthning takes place in the clouds?
Answer:
When the air gets white hot and hence a dazzling bluish white streck of light is framed, is called lightning. Normally air is a bad conductor of electricity. However, when two clouds having J e amount of positive and negative charges a proach each other, the air becomes a good conductor of electricity.

Thus the electrons from the negatively charged cloud push their way through air so as to reach to the positively charged cloud. In doing so air gets white hot and hence a dazzling bluish white hot and hence a dazzling bluish white streak of light is formed, which is called lightning. Because of this intense heat produced, the air suddenly expands and sends out huge pressure waves. These waves produced thunder.

Question 4.
How does lightning takes place between the clouds?
Answer:
Normally air is a bad conductor of electricity. However when few clouds having huge amount of positive and negative static charges approach each other, the air becomes a good conductor of electricity.

Thus the electrons from the negatively charged cloud push their way through air. So as to reach to the positively charged cloud. In doing so the air gets white hot and hence a dazzling bluish white streak of light is formed which is called lightning. Because of this intence heat produced, the air suddenly expands and sends out huge pressure causes. These waves produce thunder.

Winds, Storms and Cyclones Class 7 HBSE Notes

1. Air around us exerts pressure.
2. Air expands on heating and contracts on cooling.
3. Warm air rises up, whereas comparatively cooler air tends to sink towards the earth’s surface.
4. As warm air rises, air pressure at that place is reduced and the cooler air moves to that place.
5. The moving air is called wind.
6. Uneven heating on the earth is the main cause of wind movements.
7. Winds carrying water vapour bring rain.
8. Thunderstorms develop in hot, humid tropical areas like India very frequently. The rising temperatures produce strong upward rising winds. These winds carry water droplets upwards, where they freeze, and fall down again.
9. The swift movement of the falling water droplets alongwith the rising air create lightning and sound. It is this event that we call a thunderstorm.
10. A cyclone is a storm in which the wind blows at a speed of about 300 km per hour. Cyclones develop over oceans but never close to the equator. They never originate from the land mass but may penetrate the margins of continents.
11. A cyclone is known by different names in different parts of the world. It is called a ‘hurricane’ in the
12. American continent. In Philippines and Japan its called a ‘typhoon’ and in Australia its called ‘willywillies’.
13. It has become easier to monitor cyclones with the help of advance technology like satellites and radars.
14. Self-help is the best help. Therefore, it is better to plan in advance and be ready with defence against any approaching cyclone.

Haryana State Board HBSE 7th Class Science Solutions Chapter 11 Transportation in Animals and Plants Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 11 Transportation in Animals and Plants

HBSE 7th Class Science Transportation in Animals and Plants Textbook Questions and Answers

Question 1.
Match structures given in column I with functions given in column II.

Answer:
(i) (b)
(ii) (d)
(iii) (a)
(iv) (c)

Question 2.
Fill in the blanks :
(i) The blood from the heart is transported to all parts of the body by the __________.
(ii) Haemoglobin is present in __________ cells.
(iii) Arteries and veins are joined by a network of __________.
(iv) The rhythmic expansion and contraction of the heart is called __________.
(v) The main excretory product in human beings is __________.
(vi) Sweat contains water and __________.
(vii) Kidneys eliminate the waste materials in the liquid form called __________.
(viii) Water reaches great heights in the trees because of suction pull caused by __________.
Answer:
(i) Arteries
(ii) Red Blood Cells
(iii) Capillaries
(iv) Heart beat
(v) Urine
(vi) Urea
(vii) Urine
(viii) Transpiration

Question 3.
Choose the correct options:
(а) In plants, water is transported through :
(i) Xylem
(ii) Phloem
(iii) Stomata
(iv) Root hair
Answer:
(i) Xylem

(b) Water absorption through roots can be increased by keeping the plants :
(i) in the shade
(ii) in dim light
(iii) under the fan
(iv) covered with a polythene bag.
Answer:
(iii) under the fan

Question 4.
Why is transport of materials necessary in a plant or an animal? Explain.
Answer:
Transport of materials is necessary in plant or animal because due to it the nutrients are made available to all the parts of the body. If the transport of necessary nutrients does not take place in the body, the body will not be able to survive. So, the circulation of nutrients takes place in the whole body through the process of transportation.

Question 5.
What will happen if there are no platelets in the blood?
Answer:
The blood platelets are responsible for the clotting of the blood. When some injury occurs blood starts flowing. But it clots on its own due to the blood platelets. If there are no platelets in the blood, the blood will not be able to clot and keep on flowing through a wound or injury. This can prove fatal for the organisms as no blood will remain in the body.

Question 6.
What are stomate? Give two functions of stomata.
Answer:
There are small openings on the lower surface of the leaves and stems. These pores are called stomata. These opening are covered with guard cells. Two functions of stomata are:

• It helps in the transpiration of water i.e. the loss of excess water from the plant.
• Loss of water from the stomata creates an upward pull i.e a suction pull which helps in absorption of water to great height in tall trees.

Question 7.
Does transpiration serve any useful function in the plants? Explain.
Answer:
Transpiration is an important function in plants. It serves the following purposes:

• It helps to enhance the absorption of water by creating a suction pull.
• It helps the plant in getting rid of the excess water.
• It produces a cooling effect on the plant which prevents the heat of the sun light from damaging plants.
• It helps in transport of water and minerals to leaves and leaves use the water for the process of photosynthesis.

Question 8.
What are the components of blood?
Answer:
There are four components of the blood.

• Plasma is the liquid part of the blood which is yellowish in colour and contains 90 percent water. It contains food, enzymes, wastes and proteins etc.
• Red blood cells (R.B.Cs) are disc shaped cells containing red coloured pigment called haemoglobin in it. Haemoglobin helps in transportation of oxygen.
• White blood cells (W.B.Cs) are the fighting cells, which protect us against bacteria and foreign material causing infections
• Platelets help in clotting of the blood.

Question 9.
Why is blood needed by all the parts of a body?
Answer:
Blood is needed by all parts of the body because, it contains the digested food in it. It supplies the digested food to various parts of the body and provide essential energy to them. This energy helps the body to perform various functions and activities.

Question 10.
What makes the blood look red?
Answer:
A red coloured pigment called haemoglobin gives the blood its red colour. This pigment helps in carrying oxygen to various part of the body by blood.

Question 11.
Describe the function of the heart.
Answer:
The heart functions in the following way:
The right auricle and ventricle receives blood with carbon dioxide from all the parts of the body. The collected blood is then pumped to the lungs for the purification. In lungs the exchange of gases take place and purified blood is sent back to the left auricle. It pumps it to the left ventricle, which in turn pumps off the purified blood to all the parts of the body through arteries.

Question 12.
Why is it necessary to excrete waste products?
Answer:
The build up of waste and poisonous products in our body is always harmful. The waste products like urea etc. are toxic. When such toxic materials are not removed from the body, they get mixed with blood and can damage the cells of the body, thus proving fatal. It is, therefore, necessary to remove such poisonous waste materials from our body.

Question 13.
Draw a diagram of the human excretory system and label the various parts.
Answer:
Do it yourself.

Extended Learning – Activities and Projects

Question 1.
Find out about blood groups and their importance.
Answer:
Do it yourself.

Question 2.
When a person suffers from chest pain, the doctor immediately takes an ECG. Visit a doctor and get information about ECG. You may even look up an encyclopaedia or the internet.
Answer:
Do it yourself.

HBSE 7th Class Science Transportation in Animals and Plants Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is circulatory system?
Answer:
Circulatory system is that system which transport nutrients to various parts of the body.

Question 2.
What makes the blood red?
Answer:
A red pigment called haemoglobin makes the colour of the blood red.

Question 3.
Name various kinds of cells present in blood.
Answer:
Blood has liquid part called plasma which has Red Blood Cells, white blood cells and platelets in it.

Question 4.
What role does the red pigment haemoglobin play in our body?
Answer:
Haemoglobin gets bound with the oxygen and supplies oxygen to various parts of the body. Oxygen is essential for respiration.

Question 5.
Why platelets are important for humans?
Answer:
Platelets are very important because they cause clotting of the blood. Without platelets blood will flow from the wounds unstopped and cause death.

Question 6.
What is pulse?
Answer:
Number of times the heart beats in a minute is called pulse. In resting position pulse rate of a normal human is 72-80 beats/min.

Question 7.
What is the main difference between an artery and a vein?
Answer:
Artery carries purified blood i.e. blood carrying oxygen and vein carries blood rich in carbon dioxide.

Question 8.
What is transpiration?
Answer:
Transpiration is the loss of excess water from the leaves through the small pores called stomata.

Question 9.
What is excretion?
Answer:
Excretion is the process of throwing out the unwanted and waste products from the body.

Question 10.
What is dialysis?
Answer:
Dialysis is a process of separating small molecules from the large molecules using a semipermeable membrane.

Short Answer Type Questions

Question 1.
Explain briefly how the following are transported in plants.
(a) Water and mineral
(b) Food
Answer:
(a) Water and minerals are transported through the vascular tissues called xylem. Roots absorbs water from the soil and xylem transport it leaves prepare food by photosynthesis and this food is transported from leaves to different part by phloem.

(b) Food is transported in plants through vascular tissue called phloem.

Question 2.
What is transpiration? How is it different from translocation?
Answer:
Transpiration is the process of loosing excess water from the plants through small pores present on leaves called stomata. While the process of transportation of food through phloem is called translocation. Phloem transfer glucose from leaves to other parts of the plant while transpiration is evaporation of water to the environment.

Question 3.
List the factors affecting transpiration.
Answer:
Following factors affect transpiration in plants :
(i) Sunlight : Bright sunlight fastens the process of transpiration. No transpiration takes place during night.

(ii) Temperature : High temperature increases the rate of-transpiration while low temperature lowers the rate of transpiration.

(iii) Wind : Blowing wind increases the transpiration as water vapours are quickly removed from the leaves.

(iv) Humidity: Humid day lessens the rate of transpiration.

Question 4.
How does transportation occur in lower animals?
Answer:
The transportation occurs in lower animals through diffusion. The nutrients circulate in the body of lower animals by the flow of cytoplasm. In some multicellular aquatic plants transportation takes place by water which circulates the nutrients through their bodies.

Question 5.
What is stethoscope? What are its main parts?
Answer:
Stethoscope is an instruments used to measure the heart beat by the doctors. It has three parts :

• a chest piece that is sensitive to heart beats.
• two ear pieces.
• a tube joining the chest piece and ear pieces.

Question 6.
Write a short note on heart beat and pulse?
Answer:
Number of times a heart beats in a minute is called pulse. It can be felt by feeling the pressure of movement of blood through the artery at our wrist and by feeling the thumping of heart in our chest. It increases with physical activities. In children it varies from 90 to 100 times per minute and in adults from 70-72 beats per minute.

Question 7.
Mention the functions of the blood.
Answer:
Blood performs the following functions

• It transports nutrients to various parts of body.
• It carries oxygenated blood to different parts of the body.
• It collects deoxygenated blood from various parts of the blood and takes it to lungs for purification.
• It maintains the body temperature.
• White blood cells fight against the infections and protect us from diseases.

Question 8.
Name various organs of excretion in humans.
Answer:
Various organs of excretion in humans are :

• Lungs – for exchange of gases.
• Skin – for sweating.
• Large intestine – for excretion faeces.
• Kidneys – for excretion urine.
• Liver – for excretion excess sugar.

Question 9.
What is the importance of sweating?
Answer:
Sweat is water, salt and urea eliminated by skin in liquid form. The sweat is secreted by the sweat glands. Sweat is important in expelling the wastes like urea and salt from the body, It keeps the body cool and maintain the body temperature.

Question 10.
Explain the process of dialysis in brief.
Answer:
Process of Dialysis is used to remove the waste from the body of those people, whose kidneys are not working. Dialyses machine help in removing the waste. A tube of the machine is connected to patients blood. Blood is purified in a semipermeable membrane inside the machine and purified blood is sent back to the body.

Long Answer Type Questions

Question 1.
Explain the circulatory system in Human beings.
Answer:
The Human circulatory system consists of mainly three parts : (i) Heart, 2. Blood vessels, 3. Blood.
1. The Heart: Heart is the pumping organ present in our body. It pumps blood to all the parts of the body. It equals a clenched fist in its size. It is located in the chest cavity on the left side. It is made up of muscles and protected by a cardial membrane called paracardium. It has four chamber – two upper chambers called Auricles and two lower chambers called Ventricles. Blood is received by auricles and pumped by ventricles. The contraction and relaxations of these chambers is called the heart beat.

2. Blood vessels : Arteries, veins and capillaries are three types of blood vessels. Arteries carry oxygenated blood while veins collect deoxygenated blood. All arteries and veins are interconnected through the network of capillaries.

3. Blood : It is red coloured fluid carrying digested food to all the parts of the body and waste products to the excretory system. It has fluid portion called plasma. Plasma has Red blood cells, White blood cells and platelets in it. Red colour of the blood is due to the red pigment called haemoglobin in it. White blood cells fight against infections and platelets cause clotting of the blood.

Question 2.
Explain the Excretory System of human beings.
Answer:
Human Excretory System consists of following organs:

• A pair of Kidneys
• Ureters
• Urinary bladder
• Urethra.

→  Kidneys : Kidneys are bean shaped structures, located on each side of the backbone above the waist. Kidneys have a number of coiled tubes like structures called nephrons. Nephron consists of a Bowman’s Capsule. It is a cup like structure having a network of blood capillaries. Nephron has a long tubule surrounded by renal capillaries. Nephrons filter the excess of water salt, urea from the blood passing through it. This waste in liquid form is called urine.

→ Ureters : Ureters are long tubes passing urine formed in the kidneys to the urinary bladder. Both kidneys send a ureter to the urinary bladder.

→ Urinary bladder : Urinary bladder is an elastic sac like structure which collects the urine from ureters. Urine remains stored in it until excreted.

→ Urethra : Urethra is the opening through which the urine is passed out of the body.

Question 3.
Explain the process of transport of substances in plants.
Answer:
In plants water and minerals is transported to the leaves and other parts and similarly food is transported from leaves to all the parts of the plant.

Transport of material in plants take place through vascular tissues. There are two types of vascular tissues in plants called xylem and phloem. Xylem forms a continuous network of channels. This connects roots to the leaves through stems and through branches. This network is used to supply water and minerals to the various parts of the body. The roots absorb water from the soil and transport it to leaves and branches through xylem. This is called ascent of sap. Similarly a network of channels use to transport the food prepared by the leaves to the other parts of the plants is called phloem. This process is called translocation.

Transportation in Animals and Plants Class 7 HBSE Notes

• Every organism needs food and water to survive.
• Food and water is supplied to all parts of the bodies of the organisms by the transportation of these substances.
• Transportation of materials in human body is conducted by the circulatory system.
• Circulatory system in human beings consists of three organs : Blood, Blood vessels and Heart.
• Blood is the liquid which carries the digested food to various parts of the body.
• Blood contains liquid portion called plasma, Red blood cells, white blood cells and platelets.
• Red blood cells carry a red pigment called hemoglobin. Hemoglobin gives red colour to the blood and is responsible for carrying oxygen to all parts of body.
• White blood cells fight against the infections in our body.
• Platelets cause clotting blood.
• Blood vessels are of two types : Arteries carrying oxygenated blood to all parts of the body and veins collect deoxygenated blood from various parts of the body and take it to heart.
• Arteries and veins are interconnected with thin tubes called capillaries.
• In plants, vascular tissues are responsible for transporting food, water and minerals to the various parts of the plant.
• Xylem carries absorbed water and mineral to all parts of plant, while phloem carries food from leaves to the rest of the plant.
• After the process a digestion our body produces some waste products – these wastes are thrown out of the body and this is called excretion.
• In humans, kidneys are the main excretory organs.
• In plants excess water is thrown out by transpiration.
  Transpiration is the process of loosing excess water by evaporation through small opening on the surface of leaves called stomata.
• Dialysis is conducted to remove waste from humans body with damaged kidneys.

Haryana State Board HBSE 7th Class Science Solutions Chapter 12 Reproduction in Plants Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 12 Reproduction in Plants

HBSE 7th Class Science Reproduction in Plants Textbook Questions and Answers

Question 1.
Fill in the blanks :
(a) Production of new individuals from the vegetative part of parent is called _________.
(b) A flower may have either male or female reproductive parts. Such a flower is called _________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _________.
(d) The fusion of male and female gametes is termed as _________.
(e) Seed dispersal takes place by means of _________ and _________.
Answer:
(a) vegetative reproduction,
(b) bisexual flower
(c) pollination
(d) fertilization,
(e) wind, water, insects.

Question 2.
Describe the different methods of asexual reproduction. Give examples.
Answer:
Different methods of asexual reproduction are :
(a) Binary fission : This process takes place in unicellular organisms. Parent cell elongates and get divided into two identical daughter cells. Each daughter cell grows into an independent adult, e.g. in case of bacteria.

(b) Endospore formation : In this method a spore wall is formed around a bacterial cell to form an endospore. This endospore germinates to form an active bacterium under favourable conditions.

(c) Fragmentation : This occurs mainly in Algae. Body of the organism breaks up into two parts. Then each part grows into a new filament thus forming two organisms from a single one.

(d) Spore formation : The spores are tiny, spherical unicellular structures protected by a thick wall. The spores are stored in a hard outer covering and this is called sporangia. Under favourable conditions the hard cover breaks and spores spread for germination.

(e) Budding : In yeast, new organisms are produced by the bud formation from the parent organism. After growing to full size, the bud gets detached and form a new independent individual.

(f) Vegetative reproduction : When vegetative part of a plant like stems, leaves and root etc. give rise to new ones, it is called vegetative reproduction.

Question 3.
Explain what do you understand by sexual reproduction?
Answer:
Sexual reproduction means involvement of two parents in the process of reproduction. It is found mainly in higher plants. Male gamete and female gamete fuse to form a zygote. These zygotes develop into individuals which are not identical. Offspring inherit the characteristics of both the parents. In sexual reproduction both parents survive after the process of reproduction.

Question 4.
State the main differences between asexual and sexual reproduction.
Answer:

Question 5.
Sketch the reproductive parts of a flower.
Answer:

Question 6.
Explain the difference between self-pollination and cross-pollination.
Answer:

Question 7.
How does the process of fertilization take place in flowers?
Answer:
When the pollen grain reaches the stigma of a same flower, it starts growing out in pollen tube of the stigma. This tube continues to grow inside the style till it reaches the ovule. Male cells are released in the ovule for the fertilization with female cells and thus the zygote is formed. After this process of fertilization, the ovary develops into fruit and ovule into seeds.

Question 8.
Describe the various ways by which seeds are dispersed.
Answer:
Following are the ways in which the seeds get dispersed:
(i) Some light seeds like that of Madar, which are hairy, dry and small are carried away by the wind to different places. Some seeds having winged structure e.g. that of Maple and Drumstick are also dispersed by air.

(ii) Spiny seeds and fruits like that of Xanthium and Gokhru, the seeds stick to the clothes of passers-bye and animals. These seeds are carried away by these agents to different places.

(iii) In some cases having heavy seeds like that of Coconut, water acts as the dispersing agents.

(iv) Some seeds are diprersed when the fruit bursts like in case of Balsam and castor.

Question 9.
Match the items in Column I with those of Column II :

Answer:
(a) (iii)
(b) (v)
(c) (ii)
(d) (i)
(e) (iv)

Question 10.
Tick (✓) the correct answer :
(a) The reproductive part of a plant is the :
(i) Leaf
(ii) Stem
(iii) Root
(iv) Flower
Answer:
(iv) Flower

(b) The process of fusion of the male and the female gametes is called :
(i) fertilization
(ii) Pollination
(iii) reproduction
(iv) seed formation
Answer:
(i) fertilization

(c) Mature ovary forms the:
(i) Seed
(ii) Stamen
(iii) Pistil
(iv) Fruit
Answer:
(iv) Fruit

(d) A spore producing plant is :
(i) Rose
(ii) Bread mould
(iii) Potato
(iv) Ginger
Answer:
(ii) Bread mould

(e) Bryophyllum can reproduce by its :
(i) Stem
(ii) Leaves
(iii) Roots
(iv) Flower
Answer:
(ii) Leaves

Extended Learning-Activities and Projects

Question 1.
Make your own cactus garden by collecting pieces cut from different kinds of cacti. Grow the variety in one single flat container or in separate pots.
Answer:
Do it yourself.

Question 2.
Visit a fruit market and collect as many local fruits as possible. If many fruits are not available, you can collect tomatoes and cucumbers (these are fruits, though we use them as vegetables). Make drawings of the different fruits. Split the fruits and examine the seeds within. Look for any special characteristics in the fruits and their seeds.
Answer:
Do it yourself.

Question 3.
Think of ten different fruit-bearing plants. Remember that many vegetables are also fruits of the plants. Discuss with your teacher, parents, farmers, fruit growers and agricultural experts (if available nearby) and find out the manner of their dispersal. Present your data in the form of a table as shown below :

Answer:
Do it yourself.

Question 4.
Suppose there is one member of a particular kind of organism in a culture dish, which doubles itself in one hour through asexual reproduction. Work out the number of members of that kind of organism which will be present in the culture dish after ten hours. Such a colony of individuals arising from one parent is called a “clone”.
Answer:
Do it yourself.

HBSE 7th Class Science Reproduction in Plants Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What do you understand by the term reproduction?
Answer:
Reproduction is the process by which the living organisms produce more of their ownkind.

Question 2.
Name the methods by which plants reproduce.
Answer:
Plants reproduce in two ways :

• Asexual reproduction
• Sexual reproduction.

Question 3.
What is pollination?
Answer:
Pollination is a process in which pollen grains get transferred from anther to the stigma of the‘flower.

Question 4.
Name different methods of asexual reproduction.
Answer:
Various methods of asexual reproduction are :

• Binary fission
• Endospore formation
• Fragmentation
• spore formation
• Budding
• Vegetative reproduction.

Question 5.
What do you mean by the term fertilization?
Answer:
Fertilization is a process in which fusion of male and female gametes takes place to produce the zygote.

Question 6.
What is vegetative reproduction?
Answer:
It is the simplest method of reproduction in plants. In this method the vegetative parts like stem, roots and leaves produce new ones.

Question 7.
What is the advantage of the vegetative reproduction?
Answer:
The vegetative reproduction occurs very fast and easily. So quick reproduction is possible.

Question 8.
What is difference between unisexual and bisexual flowers?
Answer:
Unisexual flower has either a male or female reproductive part and bisexual flower has both of them.

Question 9.
Write any one advantage of seed dispersal.
Answer:
It prevents the plants from competing for sunlight, water and minerals.

Question 10.
Where are the male and female gametes found?
Answer:
The male gametes are found inside the pollen grains and the ovule contains the female gametes.

Short Answer Type Questions

Question 1.
What is reproduction? Name various methods of reproduction in plants.
Answer:
Reproduction is the process by which the living organisms produce more of their ownkind. Plants reproduce by two methods asexual and sexual. Asexual reproduction means the birth of new ones by single parent only. Sexual reproductions means involvement of two parents in the process.

Question 2.
List the different methods of asexual reproduction. In which type of plants does asexual reproduction occur?
Answer:
Asexual reproduction occurs in lower form of plants, where they do not have any reproductive part. It occurs through following methods.

• Binary fission
• Budding
• Endospore formation
• Spore formation
• Fragmentation
• Vegetative reproduction.

Question 3.
What is pollination? How is it brought about?
Answer:
The transfer of pollen grains from anther to stigma of a flower is called pollination. Pollination is brought about by many agents like water, air, animals and insects. Pollen grains are carried by these agents from anther of one flower to the stigma of another flower of same kind.

Question 4.
What do you mean by cross-pollination and self-pollination?
Answer:
Transfer of pollens occur in two ways. When pollen grains ate transferred to stigma of the same flower, it is called self pollination. When transfer of pollen grains take place from anther of one flower to the stigma of another flower of same kind, it is called cross pollination.

Question 5.
Write a short note on vegetative propagation.
Answer:
Vegetative reproduction! means the birth of new ones from the vegetative parts of the plant like leaves, stem, roots and buds. This is an asexual type of reproduction. Eyes on potato, buds sprouting on the leaves of bryophyllum, new plant growing out of cactus’ stem etc are examples of vegetative reproduction.

Question 6.
Write atleast three advantages of vegetative propagation methods.
Answer:
Following are the advantages of vegetative propagation:

• It is a fast method of reproduction.
• Plants produced by vegetative propagation have same features as that of parent plant.
• Plants produced by vegetative reproduction bear flowers and fruits earlier than the plants grown out of seeds.

Long Answer Type Questions

Question 1.
What is Asexual reproduction? Explain various methods of asexual reproduction.
Answer:
Asexual reproduction means obtaining new plants from one parent without seeds. Various methods of asexual reproduction are as follows :

Different methods of asexual reproduction are :
(a) Binary fission : This process takes place in unicellular organisms. Parent cell elongates and get divided into two identical daughter cells. Each daughter cell grows into an independent adult, e.g. in case of bacteria.

(b) Endospore formation : In this method a spore wall is formed around a bacterial cell to form an endospore. This endospore germinates to form an active bacterium under favourable conditions.

(c) Fragmentation : This occurs mainly in Algae. Body of the organism breaks up into two parts. Then each part grows into a new filament thus forming two organisms from a single one.

(d) Spore formation : The spores are tiny, spherical unicellular structures protected by a thick wall. The spores are stored in a hard outer covering and this is called sporangia. Under favourable conditions the hard cover breaks and spores spread for germination.

(e) Budding : In yeast, new organisms are produced by the bud formation from the parent organism. After growing to full size, the bud gets detached and form a new independent individual.

(f) Vegetative reproduction : When vegetative part of a plant like stems, leaves and root etc. give rise to new ones, it is called vegetative reproduction.

Question 2.
What is vegetative reproduction ? Describe vegetative reproduction in different parts of the plant.
Answer:
Vegetative reproduction means growing of off springs from the vegetative parts of the plant like roots, stems, and leaves.
(i) Vegetative propagation by roots : Thick roots of sweet potato, dahlia or asparagus give rise to new ones, inside the soil only.

(ii) Vegetative propagation by stems : In certain plants like potato, ginger, sugarcane etc, new plants grow from the stems of these plants. In potatoes these are small ‘eyes’ on the swollen stem. These eyes germinate to give rise to new plants. Ginger and turmeric also give rise to new plants rom the small buds growing on their swollen stems.

(iii) Vegetative reproduction by leaves : In plants like Bryophyllum Small plantlets grow from the margins of the leaves. These plantlets when detached from the leaf and grown develops into an independent plant.

Question 3.
Explain Sexual Reproduction in plants.
Answer:
Sexual reproduction occurs in plants having well developed reproductive parts in them. Flowers are the reproductive parts of the plant. Flowers can be unisexual i.e. having only male or female reproductive parts, and Bisexual i.e. having both male and female reproductive parts.

Female reproductive part of the flower i.e. the pistil form female ovules and male reproductive parts i.e. Androecium give rise to male gametes. When male and female gametes fuse in the ovary of the flower the process of fertilisation takes place. Male gametes are carried to the female flowers far away by agents like wind, water, insects and animals. This is called pollination. After fertilization the ovary of the flower becomes pulpy and juicy to form fruits. The ovules become the seeds.

Reproduction in Plants Class 7 HBSE Notes

• Reproduction is the process by which all the living organisms produce more of their own kind.
• The reproduction in plants occur by two methods : asexual reproduction and sexual reproduction.
• Asexual reproduction is reproduction without seeds involving only single parent.
• Asexual reproduction occurs in lower forms of the plants.
• Various methods of asexual reproduction are : Binary fission, fragmentation, Endospore formation, spore formation, Budding and vegetative reproduction.
• Binary fission is division of elongated parent cell into two daughter cell. It mostly occurs in bacteria. Some bacteria reproduce by endospore formation.
• Fragmentation is splitting up of filaments of algae in two or more than two parts, which develop into complete organism.
• Spores are formed in fungi, spores along with outer hard covering are called sporangium. Sporangium burst to release spores.
• Bud is a small bulb like projection, which comes out of yeast cell. It grows and detach from the parent cell to form a new yeast cell.
• Vegetative propagation is the birth of new ones from the vegatative parts of the plant like leaves, roots, stems etc.
• Sexual reproduction is the reproduction by seeds involving both male and female plants.
• Male and female gametes fuse to form zygote which grows into a developed new plant.
• Ovaries of the plant develop into fruit after fertilization and ovules becomes seeds.
• Male pollen grains are transferred from one flower to another and this is called pollination.
• When pollen grain of same flower are transferred from anther to stigma of same flower, it is called self-pollination.
• When pollens of a flower are transferred to stigma of another flower of same kind, it is called cross-pollination.

Haryana State Board HBSE 7th Class Science Solutions Chapter 7 Weather, Climate and Adaptations of Animals to Climate Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 7 Weather, Climate and Adaptations of Animals to Climate

HBSE 7th Class Science Weather, Climate and Adaptations of Animals to Climate Textbook Questions and Answers

Question 1.
Name the elements that determine the weather of a place.
Answer:
The temperature, humidity, rainfall, wind-seed, etc. are called the elements of the weather, that determine the weather of a place.

Question 2.
When are the maximum and minimum temperature likely to occur during the day?
Answer:
The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs generally in the early morning.

Question 3.
Fill in the blanks:
(i) The average weather taken over a long time is called ………… .
(ii) A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be………….. and ………….. .
(iii) The two regions of the earth extreme climatic conditions are …………… and ……………. .
Answer:
(i) the climate of the place
(ii) hot, dry
(iii) polar, tropical

Question 4.
Indicate the type of climate of the following areas:
(a) Jammu and Kashmir
(b) Kerla
(c) Rajasthan
(d) North-East India.
Answer:
(a) Jammu and Kashmir – moderately hot and moderately wet climate
(b) Kerala – very hot and wet climate
(c) Rajasthan – hot and dry climate
(d) North-east India – The north eastern India receives rain for a major part of the year. Therefore, we can say that the climate of the north-east is wet.

Question 5.
Which of the two changes frequently, weather or climate?
Answer:
Weather.

Question 6.
Following are some of the characteristics of animals:
(i) Diets heavy on fruits
(ii) White fur
(iii) Need to migrate
(iv) Loud Voice
(v) Sticky pads on feet
(vi) Layer of fat under skin
(vii) Wide and large paws
(viii) Bright colours
(ix) Strong tails
(x) Long and large beak
For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do yQU think that some of these characteristics can be adaptations for both the regions?
Answer:
(i) Diets heavy on fruits – tropical rainforests
(ii) White fur – polar regions
(iii) Need to migrate – pblar regions
(iv) Loud Voice – tropical rainforests
(v) Sticky pads, on feet – tropical rainforests
(vi) Layer of fat under skin – polar regions
(vii) Wide and large paws – polar Regions
(viii) Bright colours – tropical rainforests
(ix) Strong tails – tropical regions
(x) Long and large beak – tropical rainforests.

Question 7.
The tropical rainforests has a large population of animals. Explain why it is so?
Answer:
The tropical region has generally a hot climate because of its location around the equator. Even in the coldest month the temperature is generally higher than about 15°C. During hot summers, the temperature may cross 40°C. Days and nights are almost equal in length throughout the year. These regions get plenty of rainfall.

An important feature of this region is the tropical rainforests. Tropical rainforests are found in Western Ghats and Assam in India, South East Asia, Central America and Central Africa. Because of continuous warmth and rain, this region support wide variety of plants and animals. The major types of animals living in the rainforests are monkeys, apes, gorillas, lions, tigers,, elephants, leopards, lizards, snakes, birds and insects.

Question 8.
Explain, jirith examples, why we find animals of certain kind living in particular climatic conditions?
Answer:
Animals are adapted to survive in the conditions in which they live. Animals living in very cold and hot climate must possess special features to protect themselves against the extreme cold or heat.

Penguins are found in cold regions. They have a feathery coat as well as a layer of fat under the feathery coat. The coat covers their bodies right down to their legs. These adaptations keep the body warm.

Polar bear Eire found in the Arctic region where it is very cold. They have a thick layer of fur Emd a lot of fat in their bodies to keep them warm. Their soles are covered with fur to keep them warm. The white fur also helps the polar bears to blend with the snowy surroundings so that they are detected by the prey.!

Question 9.
How do elephant living in the tropical! rainforest adapt itself
Answer:
It has adapted to the conditions of rainforests in many remarkable ways. Trunks uses it as a nose because of which it has a strong sense of smell. The trunk is also used by it for picking up food. Moreover, its tusks are modified teeth. These can tear the bark of trees that elephant loves to eat. So, the elephant is able to handle the competition for food rather well. Large ears of the elephant help it to hear even very soft sounds. They also help the elephant to keep cool in the hot and humid climate of the rainforest.

Choose the correct option which answers the following questions (Question 10-12).

Question 10.
A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in:
(i) polar regions
(ii) deserts
(iii) oceans
(iv) tropical rainforests
Answer:
(iv) tropical rainforests

Question 11.
Which features adapt polar bears to live in extremely cold climate?
(i) A white fur, fat below skin, keen sense of smell.
(ii) Thin skin, large eyes, a white fur.
(iii) A long tail, strong claws, white large paws.
(iv) White ‘body, paws for swimming, gills for respiration.
Answer:
(i) A white fur, fat below skin, keen sense of smell.

Question 12.
Which option best describes a tropical region?
(i) hot and humid
(ii) moderate temperature, heavy rainfall
(iii) cold and humid
(iv) hot and dry
Answer:
(i) hot and humid

Extended Learning – Projects And Activities

Question 1.
Collect weather reports of seven successive days in the winter months (Preferably December). Collect similar reports for the summer months (Preferably June). Now prepare a Table for sunrise and sunset times as shown:

Try to answer the following questions:

• Is there any difference in the time of sunrise during summer and winter?
• When do you find that the sun rises earlier?
• Do you also find any difference in the time of sunset during the month of June and December?
• When are the days longer?
• When are the nights longer?
• Why are the days sometimes longer and sometimes shorter?
• Plot the length of the day against the days chosen in June and December. (Instructions for plotting graphs are given in Chapter 13).
  Answer:
  Do yourself.

Question 2.
Collect information about the Indian Meteorological Department. If possible visit its website: htt/www.imd.gov.in.
Write a brief report about the things this department does.
Answer:
Do yourself.

HBSE 7th Class Science Weather, Climate and Adaptations of Animals to Climate Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is raingauge?
Answer:
Rainfall is measured by an instrument called the rainguage. It is basically a measuring cylinder with a funnel on top to collect rainwater.

Question 2.
Define weather.
Answer:
The day-to-day condition of the atmosphere at,’a place with respect to the temperature, humidity, rainfall, wind speed, etc., is called the weather of that place.

Question 3.
Who prepares the weather reports?
Answer:
The weather reports are prepared by the Materological Department of the Government. This department collects data on temperature, wind etc., and makes the weather prediction.

Question 4.
Define climate.
Answer:
The average weather pattern taken over a long time, say 25 years, is called the climate of the place.

Question 5.
Why do some places have hotter climate than others?
Answer:
The places nearer to the equator are usually hotter. This is because the sun’s rays are more concentrated near the equator than they are farther North or South.

Question 6.
Give two examples of animals found in cold climates.
Answer:
(i) Penguins
(ii) Polar bear.

Question 7.
Give two examples of animals found in hot and humid climate.
Answer:
(i) Red-eyed frog
(ii) Beard ape.

Question 8.
Name three desert animals.
Answer:
(i) Camel
(ii) Snake
(iii) Lizard.

Question 9.
Can a polar bear live happily on land?
Answer:
No, it lives where the land is fully covered with snow.

Question 10.
Where do the elephant live?
Answer:
Elephant lives in forest.

Question 11.
Where does penguin live?
Answer:
Penguin lives in very cold places.

Question 12.
Define adaptation.
Answer:
The particular features of an organism that makes it suited to a particular climate is called adaptation.

Question 13.
What do you understand by ‘summer sleep’?
Answer:
Animals like frog, crocodiles and alligators live in mud during the summer months. This is called the ‘summer sleep’.

Question 14.
What do you understand by hibernation?
Answer:
During winter, some animals like bears, bats, snakes, lizards, frogs and squirrels go to sleep. This is called the winter sleep or hibernation.

Question 15.
Where do the following animals live?
(i) Monkeys
(ii) Snakes
(iii) Rabbit
(iv) Fish.
Answer:
(i) On land and trees
(ii) On land and water
(iii) On land
(iv) In water.

Question 16.
Name three animals which are active during night;
Answer:
(i) Bat
(ii) Owl
(iii) Cockroach.

Question 17.
What is the difference between climate of Kashmir and Kerala?
Answer:
Kerala is very hot and wet in comparison to Kashmir, which has a moderately hot and moderately wet.

Question 18.
Name two countries where polar regions are found?
Answer:
(i) Canada
(ii) Sweden.

Question 19.
Name two countries where the tropical rainforests are found?
Answer:
(i) India
(ii) Malaysia.

Question 20.
Name a migratory bird.
Answer:
Siberian crane.

Short Answer Type Questions

Question 1.
Why do desert animals have thick skin?
Answer:
Animals living in hot places, such as snakes, desert rats and lizards are not able to get sufficient water. So these animals have a thick skin, which prevents evaporation. Since they do not sweat, they can survive| without water for a longer time.

Question 2.
How is camel adapted live in/ desert?
Answer:
Camel lives in desert. It has long legs which help it to lift its body above the ground. Thus camel is able to avoid direct contact with the hot ground. The camel drinks water 50 litre or above in one time and store it in its body. So it lives without water for longer time. Its skin is also thick which prevents transpiration of ‘ water. Thus camel is suited to live in desert.

Question 3.
How cold place animals protect themselves from cold?
Answer:
The animals which live in cold places like waives seals, and penguins have thick skin which protects them from cold. They also have thick ,fur.

Question 4.
How fishes are adapted to live in water?
Answer:
Fishes are best suited to live in water. They have boat like structure which help them in swimming in water. They have gills from which they get oxygen and food. The body of fishes contain different types of fins which help them from swimming in water. Fishes shape tapers which provide least resistance in swimming water.

Question 5.
Why do polar bears have white fur?
Answer:
Polars bears have white fur so that they are not easily visible in the snowy white background. It protects them from their predators. It also helps them in catching their prey. To protect them from extreme cold, they have two this layers of fur. They also live a er of fair under their skin.

Question 6.
Differentiate between weather and climate.
Answer:

Question 7.
Give some examples of sea water animals.
Answer:
Almost all types of animals live in sea water. Most of the sea water animals are actively swimming animals like fishes and whales. Animals like corals, star fish, and urchin live at the bottom of the sea.s

Question 8.
Write the factors which the climate of a region depend.
Answer:
The climate of a region depends on:
(i) The presence or absence of water (rainfall).
(ii) Amount of sunshine it gets.
(iii) The ability to transfer water to the atmosphere (evaporation), and
(iv) The place whether it is a hilly or a plain region.

Question 9.
Mention the adaptive features of the animals found n cold climates.
Answer:
The animals found in cold climates have a thick layer of fat under the skin. This gives them nourishment in winter. They also have thick coat of fur on their body which helps the stay warm. The examples of animals 6 in cold regions are reindeer, arctic fox, polar bear, etc.

Question 10.
Mention the adaptations in hot and dry climates.
Answer:
Animals living in hot and dry places usually have following adaptations:
(i) Short shiny fur to reflect the sun’s rays.
(ii) Keep the body cool through sweating and panting.
(iii) To avoid the strong sun, they feed in the morning or evening and hide behind rocks and in burrows during the day.
Examples: Camel, Ostrich and Snail.

Long Answer Type Questions

Question 1.
The Earth is the only planet on which life is exists, why? Explain.
Answer:
The Earth is not the only planet revolving around the Sun. There are eight other planets that revolve Ground tfye Sun. But Earth is the only planet on which life exists. A number of factors are responsible for it. These are:
(i) Distance of Earth from the Sun; this is sufficient to keep the temperature’ on the surface of Earth at an average of 30°C; life can exist at this temperature.
(ii) The layer of carboh dioxide and watervapour which surrounds Earth prevents too much heat from leaving Earth into space; otherwise the temperature of Earth would be -30°C.
(iii) The layer of Zone which surrounds Earth does not allow ultraviolet rays to reach Earth from the sun, other wise living onganisns will die.

Question 2.
Describe the adaptive features of camel.
Answer:
The camel is the animal that thrives on the best in such hpt climate. It is also called the ship of the desert. The camel is called so because of the following adaptations it has:
(i) Thick skin that prevents water loss through perspiration or evaporation.
(ii) Humps (one or two) present in the body. These are the storehouse of fat. The camel uses this fat when food is scarce.
(iii) Pouches in the body to store water. This enables the camei to go without water for many days.
(iv) Pads of skin under the feet that act like cushions and enable the camel to walk easily in the sand without sinking.
(v) Long curly eyelashes preventing the entry of sand into eyes and thick eyebrows to protect eyes from sun. The plants and animals living in cold regions also have certain features. These are different from those possessed by plants and animals living in hot regions.

Question 3.
Defind adaptation. Mention various adaptations in terrestrial animals.
Answer:
Climate influences living organisms directly. Hence, they develop certain traits that help them to thrive well in that particular climate. This is called adaptation.

The animals that live on land are called terrestrial animals. These animals have different types of habits and ways of living. The terrestrial animals may be runners (cursorial habit), burrowers and diggers (fossorial habit), climbers (scansorial or arboreal habit) and fliers (aerial habit). Accordingly, these animals have different types of adaptations, as described below.
A. Modification of foot: Terrestrial animals have different types of foot for locomotion.
(i) Pentadactily: Terrestial animals have pentadactyl (five digits) foo; bearing claws for walking and running. Pentadactyl foot are of following three types:
(а) Plantigrade: In this type of foot, the entire palm and sole rest on the ground e.g. bear, baboon, raccoon.
(b) Digitigrade: In this case, animals perform walking and running on the digits e.g. dogs, cat, hyaena.
(c) Unguligrade: In this case, animals perform walking and running on the tips of digits covered with modified nail called hoof. The distal toe bones (unguals) are depressed or flattened, e.g. pig, horse, donkey, rhinoceros.

(ii) Bipedality: Some terrestrial animals have two footed or bipedal mode of locomotion, which spares forelimbs for other types of jobs. e.g. human beings.

B. Modification of body and head:
(i) The fast moving animals like horse, dog, etc. have streamlined body to reduce the resistance offered by the air.
(ii) In burrowing and digging animals, the head and snout are tapering. e.g. snakes, shrew, mole.

C. Modification for respiration:
The majority of terrestrial animals are lung breathers. They have lungs for respiration, e.g. Frog, lizards, all mammals.

D. Protective adaptations:
Many terrestrial animals are able to modify their form, appearance, structure or behaviour to escape predation or to increase the chances of capturing the prey. For example frog can change its body colour to match the back ground.

Question 4.
Mention various adaptations in aquatic animals.
Answer:
A large number of animals live in aquatic habitat. They include both fresh water and marine (sea water) forms. Several invt ibrates such as prawn, Octopus, some insects are aquatic or semi aquatic. A number of vertebrates such as fishes, whales, dolphins are well adapted to aquatic mode of life. They have following adaptation for aquatic mode of life.
(i) Body contour: They have streamlined laterally compressed body to reduce friction. This allows swift passage in water while swimming.
(ii) Swimming organs: The fishes have fins and whales possess flippers which help them in swimming. Frogs and ducks have webbed feet for swimming.
(iii) Protective covering: The body of fishes is covered with scales and that of frog with a mucilaginous covering, which protect them from decaying effect of water.
(iv) Gills: Fishes have special breathing organs called gills, which use dissolved oxygen of water.
(v) Swim bladder or Air bladder:
Certain fishes (bony fishes) have swim bladder or air bladder. It is filled with air and maintain buoyancy.

Weather, Climate and Adaptations of Animals to Climate Class 7  HBSE Notes

1. The day-to-day condition of the atmosphere at a place with respect to the temperature, humidity, rainfall, wind-speed, etc.; is called the weather at that place.
2. The temperature, humidity and other factors are called the elements of the weather. The weather of a place charges day after day and week after week.
3. The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs in the early morning.
4. The times of sunrise and sunset also change during the year.
5. All the changes in the weather are driven by the sun.
6. The average weather pattern taken over a long time, say 25 years, is called the climate of the place.
7. The tropical and the polar regions are the two regions of the earth, which have severe climate conditions. .
8. Animals are adapted to the conditions in which they live.
9. The polar regions are very cold throughout the year. The sun does not set for six months in a year and in the other six months it does not rise.
10. Animals in the polar region are adapted to the extremely cold climate by having some special characteristics such as white fur, strong sense of smell, a layer of fat under the skin, wide and large paws for swimming and walking etc.
11. Migration is another means to escape the harsh, cold conditions.
12. Because of the hospitable climatic conditions, huge populations of plants and animals are found in the tropical rainforests.
13. Animals in the tropical rainforests are adapted such that they eat different kinds of food to overcome the competition for food and shelter.
14. Some adaptations of animals living in the tropical rainforests include living on the trees, development of strong tails, long and large beaks, bright colours, sharp patterns, loud voice, diet of fruits, sensitive hearing, sharp eyesight, thick skin, ability to camouflage in order to protect themselves from predators etc.

Haryana State Board HBSE 7th Class Science Solutions Chapter 6 Physical and Chemical Changes Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 6 Physical and Chemical Changes

HBSE 7th Class Science Physical and Chemical Changes Textbook Questions and Answers

Question 1.
Classify the changes involved in the following processes as physical or chemical changes.
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f) Digestion of food.
Answer:
Physical Change (b), (d), (e)
Chemical Change (a), (c), (f)

Question 2.
State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
(a) Cutting a log of wood into pieces is a chemical change.
(b) Formation of manure from leaves is a physical change.
(c) Iron pipes coated with zinc do not get rusted easily.
(d) Iron and rust are the same substances.
(e) Condensation of steam is not a chemical change.
Answer:
(a) False
(b) False
(c) True
(d) True
(e) True.

Question 3.
Fill the blanks in the following statements:
(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of ………….. .
(b) The chemical name of baking soda is ……………… .
(c) Two methods by which rusting of iron can be prevented are …………. and …………. .
(d) Changes in which only …………. properties of a substance change are called physical changes.
(e) Changes in which new substances are formed are called …………. changes.
Answer:
(a) Calcium carbonate
(b) Sodium hydrogen carbonate
(c) Coating, galvanization
(d) Physical
(e) Chemical.

Question 4.
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Answer:
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas carbon dioxide.
lemon juice + baking soda → carbon dioxide + lime water
Since, a change in which one or more new substance are formed is called a chemical change, therefore this is a chemical change.

Question 5.
When a caùdie burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
Answer:
Physical Change → Melting of ware
Chemical Change → Burning of candle

Question 6.
How would you show that setting of curd is a chemical change?
Answer:
The conversion of milk into curd, i.e., setting of curd is a permanent as well as irreversible and lead to the production of a new substance. The new substance, curd is formed has different composition and properties from the milk. Hence, setting of curd is a chemical change.

Question 7.
Explain why burning of wood is cutting it into small pieces are considered as two different types of a changes.
Answer:
Burning of wood is a chemical change because, in addition to new products burning is always accompanied by production of heat.
Cutting of wood into small pieces is a physical change because, pieces of wood underwent changes in size and no new substance is formed.

Question 8.
Describe how crystals of copper sulphate are prepared.
Answer:
Take a cup full of water in a beaker and add a few drops of dilute sulphuric acid. Heat the water. When it starts boiling add copper sulphate powder slowly while stirring continuously. Continue adding copper sulphate powder till no more powder can be dissolved. Filter the solution. Allow it to cool. Do not disturb the solution when it is cooling. Look at the solution after some time. Now, you can see the crystals of copper sulphate.

Question 9.
Explain how painting of an iron gate prevents it from rusting.
Answer:
The process of rusting can be represented by the following equation:
Iron (Fe) + Oxygen (O₂ from the air) + Water (H₂O) → rust (iron oxide Fe₂O₃).

For rusting the presence of both oxygen and water (or water vapour) is essential. In fact, if the content of moisture in air is high, which means if it is more humid, rusting becomes faster. So, prevent iron gate from coming in contact with oxygen, or water, or both. One simple way is to apply a coat of paint or grease. In fact, these coats should be applied regularly to prevent rusting.

Question 10.
Explain why rusting of iron objects is faster in coastal areas than in deserts.
Answer:
The water of coastal areas contain many salts. The salt water makes the process of rust formation faster. Thus, rusting of iron objects is faster in coastal areas than deserts.

Question 11.
The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one.
(i) Process – A is a chemical change
(ii) Process – B is a chemical change.
(iii) Both processes A and B are chemical changes.
(iv) None of these processes is a chemical change.
Answer:
(iii) Both process A and B are chemical changes.

Question 12.
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.
(i) Process – A is a chemical change,
(ii) Process – B is a chemical change.
(iii) Both process A and B are chemical changes.
(iv) None of these processes is a chemical change.
Answer:
(iii) Both process A and B are chemical changes.

Extended Learning – Activities And Projects

Question 1.
Take three glass bottles with wide mouths. Label them A, B and C. Fill about half of bottle A with ordinary tap water. Fill bottle B with water which has been boiled for several minutes, to the same level as in A. In bottle C, take the same boiled water and of the same amount as in other bottles. In each bottle put a few similar iron nails so that they are completely under water. Add a teaspoonful of cooking oil of the water in bottle C so that it forms a film on its surface. Put the bottles away for a few days. Take out nails from each bottle and observe them. Explain your observations.
Answer:
Do yourself.

Question 2.
Prepare crystals of alum.
Answer:
Do yourself.

Question 3.
Collect information about the types of fuels used for cooking in your area. Discuss with your teachers/parents/others which fuels are less polluting and why.
Answer:
Do yourself.

HBSE 7th Class Science Physical and Chemical Changes Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is a physical change?
Answer:
Change in which no new product is formed.

Question 2.
What is a chemical change?
Answer:
A change in which a new substance with different properties is formed.

Question 3.
Which of the following substance contains only one kind of atoms?
copper, iron, iron sulphide, sulphur, oxygen gas, water, air and hydrogen gas.
Answer:
The following contains only one kind of atoms:
Copper, Iron, Sulphur, Oxygen gas, Hydrogen gas.

Question 4.
Which of the following substances are compounds and which are elements?
Magnesium oxide, Mercuric oxide, Carbon, Nitrogen, Potassium permagnate, Sodium carbonate.
Answer:
Elements: Carbon, nitrogen.
Compounds: Magnesium oxide, mercuric oxide, potassium permanganate, Sodium carbonate.

Question 5.
Write the symbol of the following elements:
Aluminium, calcium, chlorine, cobalt, iodine and mercury.
Answer:
Al, Ca, Cl, Co, I, Hg.

Question 6.
Ne is the symbol of neon. What else does it represent?
Answer:
This symbol represent one atom of Neon.

Question 7.
Which elements are represented by the following symbols?
Na, K, P, Pb, Ca, Zn, Br, Sn.
Answer:
Sodium, Potassium, Phosphorus, Calcium, Zinc, Bromine, Tin.

Question 8.
Name four Elements which occur in gaseous form.
Answer:
Oxygen, Nitrogen, Hydrogen and Argon.

Question 9.
When some one open a bottle of perfumes, you smell it from a distance why it is so?
Answer:
It is due to the property of gases that their molecules diffuse (move) easily in the air.

Question 10.
What is crystallisation?
Answer:
The process of separation of pure crystals of a substance from its hot and supersaturated (concentrated) solution on cooling is called
crystallisation.

Question 11.
Define chemical reaction.
Answer:
The process in which the originally present substances change into new substances is called a chemical reaction.

Question 12.
What is matter?
Answer:
Anything which occupies space and has weight is called matter. Example: Air, Water, Wood, Stone, etc.

Question 13.
What are solids?
Answer:
Any materials which has a definite shape and definite volume, at room temperature is called solid.

Question 14.
What are liquids?
Answer:
Any substance which has a definite volume but no definite shape and has one free surface is called liquids: Milk, Water, Fruit juice, Alcohol etc.

Question 15.
Name two elements that are abundantly found in air.
Answer:
The two elements that are found abundantly in air are Nitrogen element and Oxygen element.

Question 16.
Choose the elements from the following substances: Marble, Mercury, Air, Carbon.
Answer:
Mercury and Carbon are elements.

Question 17.
What is the difference between 2N and N?
Answer:
2N represent 2 atoms of nitrogen and N represent 1 molecule of nitrogen.

Question 18.
Which of the following contains only one kind of atoms?
Copper, Iron sulphide, Sulphur, Oxygen gas, Water, Air and Hydrogen gas.
Answer:
Copper, Iron, Sulphur, Oxygen gas, Hydrogen gas.

Question 19.
Which of the following substances are compounds and which are elements?
Magnesium oxide, nitrogen, potassium permanganate, sodium carbonate.
Answer:
Compounds: Magnesium oxide, Potassium permanganate, Sodium carbonate.
Elements: Nitrogen.

Question 20.
Write down the chemical symbols of the following elements: Potassium, Calcium, Phosphorus, Nitrogen, Sulphur.
Answer:
K, Ca, P₄, N and Sg.

Question 21.
Write the names of the elements having the following symbols: C, Br, P, Al, Si.
Answer:
Carbon, Bromine, Phosphorus, Aluminium and Silicon.

Question 22.
A given substance ‘X’ has definite shape, fixed volume, is in comprissible and non-diffusing. What is the physical state of the substance ‘X’?
Answer:
The substance ‘X’ is solid state.

Question 23.
Write the names of the elements which compose a molecule of water.
Answer:
Hydrogen and Oxygen.

Question 24.
Name the three most abundant elements on the earth’s crust.
Answer:
Iron, Aluminium and Silicon.

Question 25.
Give the chemical formulae of the following:
(i) Calcium hydroxide
(ii) Copper oxide
(iii) Iron chloride
(iv) Zinc nitrate
(v) Silver sulphate
(vi) Lead carbonate
(vii) Potassium phosphate
(viii) Sodium hydroxide
(ix) Hydrochloric acid
(x) Zince hydroxide.
Answer:
(i) Ca(OH)₂
(ii) CuO
(iii) FeCl₂
(iv) Zn (NO₃)₂
(v) Ag₂SO₄
(vi) PbCO₃
(vii) K₃PO₄
(viii) NaOH
(ix) HCl
(x) Zn(OH)₂.

Question 26.
Define reactents.
Answer:
The original substances that take part in a chemical reaction are called the reactants,

Question 27.
Define products.
Answer:
The substances that form as a result of chemical reaction are called the products.

Question 28.
Define chemical combination reaction.
Answer:
When two or more elements or compounds react chemically to form only one new product, then the reaction which takes place is called chemical combination.

Question 30.
Define chemical displacement reaction.
Answer:
When a more reactive element displaces a less reactive elements from its aqueous salt solution, the reaction which takes place is called chemical displacement.

Question 31.
What kind of chemical reaction takes place when a mixture of iron fillings are heated with sulphur?
Answer:
Chemical combination reaction.

Short Answer Type Questions

Question 1.
Formation of clouds is a physical change. Explain.
Answer:
Formation of clouds is a physical change. Clouds are formed by condensation of water vapours present in the atmosphere. When rainwater goes back on the earth no new product is formed. Therefore, it is a physical change.

Question 2.
Explosion of a cracker is a chemical change. Explain.
Answer:
When we burn a cracker, it exploide. Heat, light and smoke comes out after explosion. Many new products are formed. So, it is a chemical change.

Question 3.
Most physical changes are reversible. Give reasons with two examples.
Answer:
All physical changes are reversible. Because in physical changes, no new product is formed. They can be reversed easily.
Examples:
(i) Dissolving of sugar in water is a physical change and we get back sugar and water easily.
(ii) Formation of ice from water. In melting of ice, we can get water back.

Question 4.
Identify the type of change and state whether energy is evolved or absorbed in each one of the following:
Burning of a candle, lighting of a bulb, preparation of food by green plants, Volcanic eruption.
Answer:
(i) Burning of a candle: Chemical change, energy evolved.
(ii) Lighting of a bulb: Physical change, energy evolved.
(iii) Preparation of food by green plants: Chemical change, energy absorbed.
(iv) Volcanic eruption: Chemical change, energy evolved.

Question 5.
What is a chemical formula? What information does it provide?
Answer:
Chemical formula is a shorthand method of using symbols to represent the composition of a compound. Using it, we can get the following informations:
(i) Constituting name of the elements present in the compound, e.g., water has the formula H₂0. It shows that water is made up .. of two elements, hydrogen and oxygen.
(ii) Atoms present in each element, e.g.,
(iii) The composition of compound and the formula H₂O shows that in a molecule of molecular weight of the compound, this compound two atoms of hydrogen and one atom of oxygen are present.

Question 6.
What are the differences between chemical and physical changes?
Answer:
Differences between chemical and physical changes:

Question 7.
How is common salt obtained from sea water?
Answer:
In the coastal regions of India, especially in the Rann of Kutch in Gujarat and some parts of Tamil Nadu, the sea water is collected in shallow pits. It is then allowed to evaporate in the sun. As the water evaporates, the salt solution becomes supersaturated. This supersaturated solution cannot hold the excess salt. Thus, it separates out in form of salt crystals. These salt crystals are collected. They are redissolved in water and the solution is filtered to remove insoluble impurities. The clear solution is again evaporated so as to obtain the crystals of pure salt.

Question 8.
What is crystallisation? To what purpose is it put?
Answer:
The process of separation of pure crystals of a substance from its hot and supersaturated (concentrated) solution on cooling is called Crystallisation.

The process of crystallisation is employed for the separation of a pure water soluble substance from its mixture. For example, if there is a mixture of alum and common salt, the pure alum crystals can be separated by the process of crystallisation.

Question 9.
What is the significance of an equation?
Answer:
Significance of an equation:
(i) It tells us which substance reacted and which substances are produced.
(ii) It tells us the quantities of each of the reactants and each of the products.

Question 10.
Give four examples of a physical change.
Answer:
(i) Formation of dew.
(ii) Evaporation of water.
(iii) Melting of wax.
(iv) Making of ice-cream.

Question 11.
Give four examples of a chemical change.
Answer:
(i) Photosynthesis by plants.
(ii) Clotting of blood.
(iii) Curdling of milk.
(iv) Burning of candle.

Question 12.
State four characteristics of physical change.
Answer:
(i) It is temporary.
(ii) It is reversible.
(iii) No new substance is produced.
(iv) No change in the chemical properties.

Question 13.
State four characteristics of chemical change.
Answer:
(i) It is permanent.
(ii) It is irreversible.
(iii) New substance is produced.
(iv) Changes in the chemical properties due to the formation of new substances.

Question 14.
What happens when an iron blade of a knife is dipped in copper sulphate solution? What kind of chemical reaction takes place?
Answer:
When an iron blade of a knife is dipped in copper sulphate solution iron blade is coated with reddish deposit of copper. Thus, we can say that iron (more reactive element), displaces copper (less reactive element), from its aqueous copper sulphate solution. Chemical displacement reaction is takes place.

Question 15.
Why do the molecules in a liquid tend to stay together and give a condensed form?
Answer:
In a liquid, the molecular motion are not great enough to over come the force of attraction between molecules. That is why the molecules tend to stay together and give a condensed form.

Question 16.
On a hot summer day the cycle tubes burst suddenly. Explain why?
Answer:
The cycle tubes are filled with air. On a hot summer day, the temperature of the atmosphere is high. When cycle runs on the road, the friction between the cycle wheel and the path produces heat which raises the temperature of the air in the cycle tubes. On heating the air expands and exerts pressure in the inside of the tubes. Due to the pressure, the cycle burst suddenly on a hot summer day.

Question 17.
Why can the same substance exist in all the three states, that is, solid liquid and gas?
Answer:
The space between the molecules, the force of attraction between the molecules, and the amount of movement of the molecules of a substance can be changed by changing the pressure and temperature of the substance. So depending on the pressure and temperature, the same substance can exist in all the three states i.e., Solid, liquid and gaseous. For example under normal pressure water exists as a solid in the form of ice at a temperature of 0°C or below. It exists as a liquid in the form of water at the room temperature and as a gas in the form of steam at 100°C or above.

Question 18.
Write some important properties of an element.
Answer:
Properties of an element are:
(i) An element is made up of some kinds of atoms.
(ii) An element cannot be Broken up into much simpler substances,
(iii) An element can be represented by a chemical symbol.

Question 19.
What are the important characteristics of a compound?
Answer:
(i) Chemical compound is made up of two or more elements combined chemically.
(ii) They have fixed formula or composition.
(iii) They have fixed melting point (M.P.) and boiling point (B.P.).
(iv) Energy is either evolved or absorbed during formation of a compound.
(v) Properties of constituent elements are different from its compound, e.g., properties of water (H₂O) are different from properties of hydrogen and oxygen.

Question 20.
What does the formula CO₂ represent?
Answer:
Molecular formula CO₂ represents:
(i) the name of the compound carbon dioxide.
(ii) carbon dioxide is made up of two kinds of elements – carbon and oxygen.
(iii) one molecule of carbon dioxide has one atom of carbon and 2 atoms of oxygen.
(iv) the molecular mass of carbon dioxide is 12 + 2 x 16 = 44 gram.

Question 21.
How is salt obtained from sea-water?
Answer:
The seas are great sources of salts. A litre of a water contains about 35 grams of salts. Sodium chloride is the main salt. The sea-water is trapped in shallow called lagoons and is allowed to evaporate in sunlight to white solid crystal of salts. These crystals are processed and packed to send the markets.

Question 22.
Give three reasons for supporting that water is a compound and not a mixture.
Answer:
Water is considered a compound due to the following reasons:
(i) Water cannot be separated into its constituents, hydrogen and oxygen, by the physical process.
(ii) The properties of water are entirely different from those of its constituents hydrogen and oxygen.
(iii) Water contains hydrogen and oxygen combined together in a fixed proportions of 1:8 by weight.

Question 23.
Explain why solution of salt in water is considered a mixture and not a compound. Give three reasons.
Answer:
Salt solution is considered a mixture due to the following reasons:
(i) Salt solution can be separated into salt and water by the physical process.
(ii) Salt solution, shows the properties of both its constituents salt as well as water.
(iii) The composition of salt solution is variable i.e., the percentage of salt and water in different salt solutions are different.

Question 24.
What information do we get from a chemical equation?
Answer:
The informations obtained from a chemical equation are:
(i) Name of the substance (elements or compound) taking part in reaction, i.e., reactants and products.
(ii) The number of atoms and molecules of different substances.
(iii) The conditions under which the reaction takes place or taking part in reaction, for example:
N₂ + 3H₂ → 2NH₃
It represents 1 molecule of nitrogen combines with 3 molecules of hydrogen to form 2 molecules of ammonia.

Question 25.
“In a chemical reaction, there is only a rearrangement of the atoms of the reactants.” Explain this statement giving an example.
Answer:
In a chemical reaction, there is only a x’e. angement of the atoms of the reactants because when a chemical reaction occurs new products are formed. These products have same kind and number of atoms as are present in reactants. They are only rearrange to give new substances. For example, in a reaction between iron and sulphur to give iron sulphide the number of atoms of iron and sulphur are identical on both sides of the equation.
Fe + S → FeS (On heating)

Question 26.
What is done to make a chemical equation more informative?
Answer:
To make a chemical equation more informative it should be balanced and conditions of the reaction should be written above the arrow. For example,

It shows that 2 molecules of water on electrolysis break up into 2 molecules of hydrogen and 1 molecule of oxygen.

Question 27.
What do you understand by reactants and products?
Answer:
Reactants: Substances taking part in a reaction are called reactants. They are written on the left side of the chemical equation.
Products: Substances produced in a reaction are called products. They are written on the right side of the equation.
Example:

Long Answer Type Questions

Question 1.
What does a chemical formula represent?
Answer:
Significance of chemical formula:
(i) It represents the name of the substance.
(ii) It represents one molecule of the substance.
(iii) It gives the names of all the elements present in the molecule.
(iv) It represents the mass of one molecule.

As an example of the formula of H₂SO₄:
(i) Represents sulphuric acid.
(ii) Represent one molecule of sulphuric acid.
(iii) Tells that sulphuric acid contains three elements:
hydrogen, sulphur, and oxygen.
(iv) Tells that one molecule of sulphuric acid contains two atoms of hydrogen; 1 atom of sulphur and 4 atoms of oxygen.

Question 2.
What do you understand by the following terms? Give examples.
(i) Endothermic chemical change
(ii) Exothermic chemical change.
Answer:
(i) Endothermic chemical change: When a chemical change takes place with the absorption of heat energy, then the change is said to be endothermic. .
Examples: Heating of mercuric oxide to form mercury and oxygen. Heating of calcium carbonate to form calcium oxide and carbon dioxide.

(ii) Exothermic chemical change: When a chemical change takes place with the liberation of heat energy, the change is said to be exothermic.
Examples: Candle on burning liberates heat and light energy. Respiration is an exothermic change.

Question 3.
What is a compound? How does it differ from a mixture?
Answer:
A compound consists of two or more elements, joined together in a fixed ratio by chemical bonds. For example, water formed from hydrogen and oxygen, sodium chloride formed from sodium and chlorine, sugar formed from carbon, hydrogen and oxygen, nitre formed from potassium, nitrogen and oxygen are all compound.
Difference between compounds and mixtures:

Question 4.
What is the difference between a balanced and unbalanced chemical equations? Explain with an example.
Answer:
Difference between a balanced and unbalanced chemical equations:
In unbalanced chemical equations, the number of each element atoms do not same. As for example:
Mg + O₂ → MgO.
This is not a balanced equation because the number of Mg atom and oxygen atoms are not same on both the sides, Le., reactants and product sides. On the other hand, in a balanced chemical equation the number of each atoms of each elements on both sides should be equal. As for example:
2Mg + O₂ → 2MgO.
In this balanced chemical equation the number of magnesium atoms and oxygen atoms in the left hand side are equal to the right hand side of the equation. So it is a balanced chemical equations.
(i) A mixture consists of two or more chemically different substances.
(ii) The composition of mixture can be separated easily by simple means.
(iii) Its formation is not accompanied by absorption or evolution of heat, light or electricity.
(iv) Mixture do not have definite formula.
(v) Mixture do not have fixed M.P. and B.P.
(vi) Mixture can be homogeneous and heterogenous.

Question 5.
Balance the following equations:
(i) Fe + O₂ → Fe₂O₃
(ii) H₂O + H₂ → O₂
(iii) Mg + O₂ → MgO
(iv) Al + O₂ → Al₂O₃
(v) Fe + HCl → FeCl₃ + H₂
(vi) Cu + O₂ → CuO
(vii) Hg + O₂ → HgO
(viii) Zn + HCl → ZnCl₂ + H₂
(xi) Al + HCl → AlCl₃ + H₂
(x) N₂ + H₂ → NH₃
Answer:
(i) 4Fe + 3O₂ → 2Fe₂O₃
(ii) 2H₂O → 2H₂ + O₂
(iii) 2Mg + O₂ → 2MgO
(iv) 4Al + 3O₂ → 2Al₂O₃
(v) 2Fe + 6HCl → 2FeCl₃ + 3H₂
(vi) 2Cu + O₂ → 2CuO
(vii) 2Hg + O₂ → 2HgO
(viii) Zn + 2HCl → ZnCl₂ + H₂
(xi) 2Al + 6HCl → 2AlCl₃ + 3H₂
(x) N₂ + 3H₂ → 2NH₃

Physical and Chemical Changes Class 7  HBSE Notes

1. Properties such as shape, size, colour and state of a substance are called its physical properties.
2. A change in which a substance undergoes a change in its physical properties is called a physical change. A physical change generally reversible.
3. A change in which one or more new substances are formed is called a chemical change. A chemical change is also called a chemical reaction.
Some common examples of chemical change:
1. Burning of wood or charcoal.
2. Burning of Candle.
3. Decomposition of water into hydrogen and oxygen.
4. Formation of water from hydrogen and oxygen.
5. Digestion of food.
6. Curdling of milk.
7. Formation of biogas (Crobar gas).
8. Burning of petrol or diesel.
9. Smoking of cigarette.
10. Drying of paint.
11. Rusting of iron.
12. Ripening of fruit.
13. Baking of cake.
14. Photosynthesis by plants.
15. Formation of wine.

Some Common Examples of Physical Changes:
1. Formation of dew.
2. Evaporation of water.
3. Crystallisation of sugar from its solution.
4. Ringing of an electric bell.
5. Breaking of glass pane.
6. Making of ice-cream.
7. A rock rolling down a hill.
8. Bending of glass tube by heating.
9. Melting of wax.
10. Sublimation of camphor.

4. If you leave a piece of iron in the open for some time, it acquires a film of brownish substance. This substance is called rust and the process is called rusting.
5. Any pure substance which cannot be broken into two or more pure substances by any chemical means is called an element.
6. The smallest unit of an element, which takes part in a chemical reaction is called an atom.
7. The smallest unit of a pure substance, which always exists independently and can retain physical and chemical properties of that substance, is called a molecule.
8. A metal is an element which is generally malleable, ductile and a good conductor of heat and electricity. About 80% of the elements are metals.
9. Non-metals are bad conductors of heat and electricity. They are neither malleable nor ductile. Non-rr Hals are generally soft.
10. When the molecule of a substance contains two or more atoms of different elements, combined together in a definite ratio, then it is said to be a molecule of a compound.
Symbols of common elements (Metals)

11. When one or more substances (elements or compounds) undergo a chemical change, with the absorption or release of energy, so as to form one or more new products, then the change taking place collectively is called chemical combination.
12. When two or more elements or compounds react chemically to form only one new product, then the reaction which takes place is called chemical combination.
13. When a single chemical compound decomposes on heating or by some other kind of energy, so as to form two or more new substances (elements or compounds), then the chemical reaction which takes place is called chemical decomposition.
14. When a more reactive element displaces a less reactive element from its aqueous salt solution, the reaction which takes place is called chemical displacement.
15. When an acid solution reacts with a base or metal carbonate, so as to form a salt, then the reaction is called neutralisation reaction.
16. The process of separation of pure crystals of a substance from its hot and supersaturated (concentrated) solution on cooling is called crystallisation.

Haryana State Board HBSE 7th Class Science Solutions Chapter 13 Motion and Time Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 13 Motion and Time

HBSE 7th Class Science Motion and Time Textbook Questions and Answers

Question 1.
Classify the following as motion along a straight line, circular or oscillatory motion :
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry go round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bed.
(vi) Motion of a train on a straight bridge.
Answer:
(i) Oscillatory
(ii) along a straight, line
(iii) circular
(iv) oscillatory
(v) oscillatory
(vi) along a straight line.

Question 2.
Which of the following is not correct?
(i) The basic unit of time is second.
(ii) Every object moves with a constant speed.
(iii) Distance between two cities are measured in kilometres.
(iv) The time period of a given pendulum is not constant.
(v) The speed of a train is expressed in m/h.
Answer:
(ii), (iv) (v).

Question 3.
A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?
Answer:
Time period of a pendulum is time taken to complete 1 oscillation
Time taken to complete = 32 s.
20 oscillations
Time taken to complete = \(\frac { 32 }{ 20 }\)s.
1 oscillation
= 1.6 s.
∴ Time period of pendulum is 1.6 seconds.

Question 4.
The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
Answer:
Distance = 240 km.
Time taken = 4 hr.
Speed = \(\frac { Distance covered }{time taken }\)
= \(\frac { 240 }{ 4 }\) \(\frac { km }{ h }\)
= 60 km/h.
Speed of the train is 60 km/h.

Question 5.
The odometer of a car reads 57321.0 km when the clock shows the time 08:30 AM. What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/ h also.
Answer:
Distance = 57336.0 km – 57321 km = 15 Km
Time = 8.50 Am. – 8.30 Aim. = 20 min
Speed = \(\frac { Distance }{ time }\) = \(\frac { 15 }{ 20 }\) km/m
= 0.75 km/m. = 45 km/h

Question 6.
Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s. Calculate the distance between her house and’the school.
Answer:
Time taken = 15 min
Speed = 2 m/s.
Distance = Speed x time
= 15 x 2
= 30 m.
So, distance between Salma’s School and her house is 30 metre.

Question 7.
Show the shape of the distance-time graph for the motion in the following cases :
(i) A car moving with a constant speed.
(ii) A car parked on a side road.
Answer:

Question 8.
Which of the following relations is correct?
(i) Speed = Distance x Time
(ii) Speed = \(\frac { Distance }{ Time }\)
(iii) Speed = \(\frac { Time }{ Distance }\)
(iv) Speed = \(\frac { 1 }{ Distance x Time }\)
Answer:
(ii) Speed = \(\frac { Distance }{ Time }\) is correct.

Question 9.
The basic unit of speed is :
(i) km/min
(ii) m/min
(iii) km/h
(iv) m/s
Answer:
(iv) m/s

Question 10.
A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is :
(i) 100 km
(ii) 25 km
(iii) 15 km
(iv) 10 km
Answer:
(ii) 25 km

Question 11.
Suppose, the two photographs shown in Fig. 13.1 and Fig. 13.2, had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs. Calculate the speed of the blue car.
Answer:
0.1 cm/s or 10 m/s.

Question 12.
Fig. 13.16 shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?

Answer:
‘A’ car is moving faster.

Question 13.
Which of the following distance-time graphs shows a truck moving with speed which is not constant?

Answer:

Extend Learning – Activities and Projects

Question 1.
You can make your own sundial and use it to mark the time of the day at your place. First of all find the latitude of your city with the help of an atlas. Cut out a triangular piece of a cardboard such that its one angle is equal to the latitude of your place and the angle opposite to it is a right angle. Fix this piece, called gnomon, vertically along a diameter of a circular board a shown in Fig. 13.4. One way to fix the gnomon could be to make a groove along a diameter on the circular board.

Next, select an open space, which receives sunlight for most of the day, Mark a line on the ground along the North-South direction. Place the sundial in the sun as shown in Fig. 13.4 Mark the position of the tip of the shadow of the gnomon on the circular board as early in the day as possible, say 8:00 AM. Mark the position of the tip of the shadow every hour throughout the day. Draw lines to connect each point marked by you with the centre of the base of the gnomon as shown in Fig. 13.4. Extend the lines on the circular board up to its periphery. You can use „ this sundial to read the time of the day at your place. Remember that the gnomon should always be placed in the North- South direction as shown in Fig. 13.4.

Answer:
Do it yourself.

Question 2.
Collect information about time-measuring devices that were used in the ancientitimes in different partrs of the world. Prepare a brief write up on each one of them. The write up may include the name of the device, the place of its origin, the period when it was used, the unit in which the time was measured by it and a drawing or a photograph of the device, if available.
Answer:
Do it yourself

Question 3.
Make a model of a sand clock which can measure a time interval of 2 minutes (Fig. 13.5).

Answer:
Do it yourself

Question 4.
You can perform an interesting activity when you visit a park to ride a swing. You will require a watch. Make the swing oscillate without anyone sitting on it. Find its time period in the same way as you did for the pendulum. Make sure that there are no jerks in the motion of the swing. Ask one of your friends to sit on the swing. Push it once and let it swing naturally. Again measure its time period. Repeat the activity with different persons sitting on the swing. Compare the time period of the swing measured in different cases. What conclusions do you draw from this activity?
Answer:
Do it yourself.

HBSE 7th Class Science Motion and Time Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is motion?
Answer:
Motion is the change in the position of a body with respect to time and its surroundings.

Question 2.
What is uniform motion?
Answer:
When a body covers equal distance in equal intervals of time, the motion is called uniform motion.

Question 3.
What is speed?
Answer:
Speed is the distance covered by a body in a unit time.

Question 4.
Write one way in which people used to measure time in early days?
Answer:
People used to measure time with the help of Sundials.

Question 5.
What is the use of stop-watch?
Answer:
Stop-watch is used to measure exact time in case of athletic events as it can be stopped and started any moment.

Question 6.
What is a pendulum?
Answer:
A pendulum is a small non-magnetic ball like body, suspended by a light string.

Question 7.
What is a uniform motion?
Answer:
Motion of a body along a straight line covering equal distances in equal intervals of time is called a uniform motion.

Question 8.
What are the units of measuring speed?
Answer:
Speed is measured in metre per second (m/s) or kilometre per hour (km/h).

Short Answer Type Questions

Question 1.
Distinguish between uniform and non-uniform motion.
Answer:
Uniform motion is the equal distances covered in equal intervals of time. It means body moves with a constant speed. Non-uniform motion is the unequal distances covered in equal intervals of time. It means the body moves with unconstant speed.

Question 2.
How can we make a pendulum of our own? What is the time period of a pendulum?
Answer:
We can make a pendulum by susptending a metal ball with a cotton thread. The other end of the thread can be tied to some support. The time taken by a pendulum to complete its to and fro movement i.e. one oscillation is called the time period of the pendulum.

Question 3.
How can we determine the motion made by any body to be uniform or non-uniform with the help of a distance – time graph?
Answer:
If the distance – time graph obtained shows a straight line, the motion of the body is said to be uniform and if we obtain a curved line on a distance time graph that means the body is undertaking non-uniform motion. Thus a distance time graph helps in determining the uniform or non-uniform speed of the body.

Question 4.
A train is running at a speed of 50 km/h. How long will it take to cover a distance of 250 km.?
Answer:
Speed = 50 km/h
Distance = 250 km.
Time = ?
S = \(\frac { d }{ t }\)
50 = \(\frac { 250 }{ t }\)
∴ t = \(\frac { 250 }{ 50 }\) hr = 5 hr.

Question 5.
Shatabdi Express takes 6 hours to reach Lucknow, at a speed of 60 km/h. Find the distance it travels.
Answer:
Time = 6 hr.
Speed = 60 km/h
Distance = Speed x time
= 60 x 6 = 360 km
∴ Shatabdi travels 360 km at a speed of 60 km/h in 6 hr.

Question 6.
A car travels a distance of 200 km at the speed of 50 km/h. Calculate the time taken to cover the distance.
Answer:
Distance = 200 km
Speed = 50 km/h
Time = \(\frac { Distance }{ Speed }\) = \(\frac { 200 }{ 50 }\) = 4h
Car will take 4 h to cover the distance.

Long Answer Type Questions

Question 1.
Given below is a table showing time taken by a car to travel various distances. What do you infer from this data?

Answer:
We see that the car covers the distance of first 10 m in 1 sec. It again covers the distance of 10 m in another time of 1 sec i.e. 2-1 = 1 sec. So, we find that the car covers every 10 m in each 1 sec. It means that the car is covering equal distance in equal interval of time. When a body covers equal distance in equal intervals of time, it is said to be in a uniform motion. So, this data shows that the car is moving with a constant speed.

Question 2.
Describe various methods used to measure time in earlier times?
Answer:
There were no electronic watches in earlier times. Measuring time was a little bid difficult. The earliest method of measuring time was based on the position of the Sun. The Sundials were used for this purpose. Time was measured by the shadow casted by the changing position of the Sun from day to night. Chinese made a water clock 6000 years ago. Sand Clock was also used to measure time. Sand Clock was used by Romans. The time taken by sand to fall into the lower chamber from the upper chamber was considered to be the unit of measuring time. The discovery of pendulum helped in determining the exact time before the electronic watches were invented.

Question 3.
What is a pendulum? How does it help in determing time?
Answer:
Pendulum is a simple device which shows periodic motion. A simple pendulum consists of a non-magnetic metal ball called bob. This bob is suspended with help of a string. The open end of the string is tied to a support. Bob of the pendulum is held at a side and released. It starts moving in a to and fro motion. This is called an oscillatory motion. The time taken by the pendulum to complete one oscillation is called time period. This time period is always same with a pendulum having same length. Time period changes with the change in the length of the string. The string of the pendulum is adjusted to the length, that it completes one oscillation in second and it keeps on moving the clock giving us time.

Motion and Time Class 7 HBSE Notes

• Motion is the change in the position of an object with respect to its surroundings.
• Motion can be of many types. It can be along a straight line, circular, oscillatory.
• Motion can be uniform or non-uniform motion.
• Uniform motion means equal distance covered in equal intervals of time. It means a constant motion.
• Non-uniform motion means unequal distance covered in equal intervals of time.
• Distance moved by an object in unit time is called its speed.
• Basic unit of measuring speed is (m/s) meter / second.
• Time is measured in respect to the periodic motions.
• Pendulum was the first device to measure time exactly.
• In earlier days time Was measured by various objects like sundials, sand clocks, water clocks, etc.
• With the discovery of pendulum, devices to measure exact time were invented.
• Now-a-days various devices like stop-watch and other electronic devices are used to measure time intervals smaller than even a second.
• Distance time graph gives us an idea about the motion of the object. Straight-line obtained on this graph depicts constant motion, while non-constant motion is depicted by various shapes on the graph.

Haryana State Board HBSE 7th Class Science Solutions Chapter 5 Acids, Bases and Salts Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 5 Acids, Bases and Salts

HBSE 7th Class Science Acids, Bases and Salts Textbook Questions and Answers

Question 1.
State differences between acids and bases.
Answer:

Question 2.
Ammonia is found is many household products, such as window cleaners. It turns red litmus blue, what is its nature?
Answer:
Basic.

Question 3.
Name the source from which litmus solution is obtained. What is the use of this solution?
Answer:
Litmus solution is extracted from lichens. It has a mauve (purple) colour in distilled water. When added to an acidic solution, it turns red and when added to a basic solution, it turns blue. It is available in the form of a solution, or in the form of strips of paper.

Question 4.
Is the distilled water acidic/basic/ neutral? How would you verify it?
Answer:
The distilled water is neutral. Put a drop of the distilled water on a strip of the red litmus paper with the help of a droper. We observe that colour of the litmus paper as not change.

The solutions which do not change the colour of either red or blue litmus are known as neutral solutions. These substances are neither acidic nor basic.

Question 5.
Describe the proeess of neutralization with the help of an example.
Answer:
The process due to! which an acid completely reacts with a base to form salt and water as the only products is called neutralization.
Acid + Base → Salt + Water
Example: Hydrochloric add (HCl) + Sodium hydroxide (NaOH)
Sodium chloride (NaCl) + Water (H₂O)

Question 6.
Make “T” if the statement is true and ‘F’ if it is false.
(i) Nitric acid turn red litmus blue.
(ii) Sodium hydroxide turns blue litmus red.
(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water.
(iv) Indicator is a substance which shows different colours in acidic and basic solutions.
(v) Tooth decay is caused by the presence of a base.
Answer:
(i) Flase
(ii) Flase
(iii) True
(iv) True
(v) True.

Question 7.
Dorji has a few bottles of soft drink in his restaurant. But unfortunately, these are not labelled. He has to serve the drinks on the demand of customers. One customer wants acidic drink, another wants basic and third one wants neutral drink; How will Dorji decide which drink is to be served to whom?
Answer:
Do yourself.

Question 8.
Explain why?
(a) An antacid tablet is taken when you suffer from acidity.
(b) Calamane solution is applied on the skin when an ant bites.
(c) Factory waste is neutralised before disposing it into the water bodies.
Answer:
(a) Our stomach contains hydrochloric acid. It help us to digest food. But too much of acid in the stomach causes indigestion. Sometimes indigestion is painful. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralises the effect of excessive acid.

(b) The sting of an ant contains formic acid. When an ant bites, it injects the acidic liquid into the skin. The effect of the sting can be neutralised by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains Zinc carbonate.

(c) The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms. The factory wastes are, therefore, neutralised by adding basic substances.

Question 9.
Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you Identify them? You have only turmeric indicator.
Answer:
Do yourself.

Question 10.
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
Answer:
The nature of the solution is neutral, because the solutions which do not change the colour of either red or blue litmus are known as neutral solution. These substances are neither acidic nor basic.

Question 11.
Consider the following statements:
(a) Acids and bases both change colour of all indicators.
(b) If an indicator gives a colour change with an acid, it does not give a change with a base.
(c) If an indicator changes colour with a base, it does not change colour with an acid.
(d) Change of colour in an acid and a base depends on the type of the indicator. Which of these statements are correct?
(i) All four
(ii) a and b
(iii) b and c
(iv) only d
Answer:
(ii) a and b.

Extended Learning – Activities And Projects

Question 1.
Using the knowledge of acids and bases, write a secret message with the help of baking soda and beet’root. Explain how it works.
(Hint: Prepare baking soda solution in water. Use this solution to write the message on a sheet of white paper with a cotton bud. Rub a slice of fresh beet root over the message.)
Answer:
Do yourself.

Question 2.
Prepare red cabbage juice by boiling a piece of red cabbage in water. Use it as an indicator and test the acidic and’ basic solutions with it. Present your observations in the form of a Table.
Answer:
Do yourself.

Question 3.
Bring the soil sample of your area, find out if it is acidic, basic or neutral. Discuss with farmers if they treat the soil in any manner.
Answer:
Do yourself.

Question 4.
Visit a doctor. Find out the medicines be prescribes to treat acidity. Ask him how acidity can be prevented.
Answer:
Do yourself.

HBSE 7th Class Science Acids, Bases and Salts Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is an acid Id
Answer:
A substance which dissolves in water to give hydrogen ions as the only positively charged ions’fs called an acid.

Question 2.
What are mineral acids? Give, three examples.
Answer:
The acids which are prepared from the minerals of the Earth are called mineral acids.
Examples: Sulphuric acid, Nitric acid, Hydrochloric acid.

Question 3.
What are organic acids? Give three examples.
Answer:
Organic acids are found in plant and animal products, for examples, oxalic acids, citric acid, acetic acid, etc.

Question 4.
A solution turns red litmus solution blue. Is the solution acidic or basic in nature?
Answer:
Basic.

Question 5.
Give two examples each of (i) Strong bases (ii) Weak bases.
Answer:
(i) Strong bases: Sodium hydroxide, potassium hydroxide.
(ii) Weak bases: Copper hydroxide, zinc hydroxide. .

Question 6.
What do you understand by the term “neutral substance?”
Answer:
The substances which do not bring about any change in the colour of common indicators are called neutral substances.

Question 7.
Name the acids present in:
(i) Vinegar
(ii) Lemon juice
Answer:
(i) Acetic acid (CH₃COOH)
(ii) Citric acid.

Question 8.
Write the names of three mineral acids.
Answer:
(i) Sulphuric acid (H₂SO₄)
(ii) Nitric acid (HNO₃) and
(iii)Hydrochloric acid (HCl) are mineral acids.

Question 9.
Which of the following are oxides?
H₂O, CO, Co, NO, CO₂ , NaOH
Answer:
Oxides: H₂O, CO, NO and CO₂.

Question 10.
From the following list select metallic oxide and non-metallic oxides: CaO, Fe₂O₃, N₂O₅, CO₂, Na₂O, SO₂.
Answer:
(i) Metallic oxide: CaO, Fe₂O₃ and Na₂O.
(ii) Non-metallic oxide: N₂O₅, CO₂ and SO₂.

Question 11.
What are indicators?
Answer:
The complex, naturally occurring substances, which change their colour on coming in contact with other substances are called indicators. Turmeric, litmus, china rose etc. are some indicators.

Question 12.
Name two neutral liquids.
Answer:
(i) Alcohol
(ii) Ether.

Question 13.
Name two neutral gases.
Answer:
(i) Hydrogen, (ii) Oxygen.

Question 14.
Name two neutral solids.
Answer:
(i) Common Salt
(ii) Sugar.

Question 15.
What do you understand by term concentrated acid?
Answer:
The acids which contain very little or no amount of water are called concentrated acids.

Question 16.
What are dilute acids?
Answer:
The acids which contain a large amount of water (or solutions of acids in water) are called dilute acids.

Question 17.
Name the kind of substance formed when an acid reacts with a base.
Answer:
Neutralised.

Question 18.
What is missing in the following equation?
Fat + ……. → Soap + Glycerol
Answer:
Fat + NaOH → Soap + Glyceral
Thus NaOH missing from the equation.

Question 19.
An element combines with oxygen to form an oxide. This oxide dissolves in water. This aqueous solution changes blue litmus to red. Write:
(i) The nature of element (metal or non-metal)
(ii) The general name of the oxide.
Answer:
(i) The element is non-metal.
(ii) General name of the oxide non-metallic oxide.

Question 20.
What happens when a non-metal oxide is dissolved in water?
Answer:
When a non-metal oxide is dissolved in water, it forms acids. Examples:
(i) CO₂ + HO₂ → H₂CO₃ (Carbonic acid).
(ii) SO₂ + HO₂ → H₂SO₃(Sulphuric acid).

Question 21.
State one characteristics, property of all acids.
Answer:
All acids contain replaceable hydrogen.

Question 22.
Name the gas obtained when a metal carbonate reacts with an acid.
Answer:
When a metal carbonate reacts with an acid, carbon dioxide gas is envolved. Example:

Question 23.
Write equations for the action of water on:
(i) MgO
(ii) Calcium oxide.
Answer:
(i) MgO + H₂O → Mg(OH)₂ (Magnesium hydroxide)
(ii) CaO + H₂O → Ca(OH)₂(Calcium hydroxide)

Question 24.
What are mineral acids? Give two examples.
Answer:
Mineral acids are those acids which are obtained from the earth. Examples, Sulphuric acid, Nitric acid.

Question 25.
Name the three salts which are commonly lised at home..
Answer:
Three, salts commonly used at home are:
(i) Sodium chloride
(ii)Sodium carbonate
(iii) Sodium hydrogen carbonate.

Question 26.
Give the chemical formula of slaked lime
Answer:
Chemical formula of slaked lime is Ca(OH)₂

Question 27.
Name one/compound of calcium which is used for bleaching cloth.
Answer:
Bleaching powder.

Question 28.
What is the formula of sulphuric acid?
Answer:
The formula of sulphuric acid is H₂SO₄.

Question 29.
A solution turns red litmus paper blue. What does this indicate about the chemical nature of the solution?
Answer:
The chemical nature of the solution is acidic.

Question 30.
What do you understand by anhydrous salt?
Answer:
Hydrated salts loose their water of crystallisation upon heating. They love their shape and colour also and becomes powered. They are called anhydrous salts.

Question 31.
Name two normal salts.
Answer:
(i) Sodium Chloride (NaCl)
(ii) Potassium nitrate (KNO₃).

Question 32.
Name two basic sdlts.
Answer:
(i) Calcium hydrdgen chloride [Ca(OH)Cl]
(ii) Magnesium hydroxy chloride [Mg(OH)Cl] etc.

Question 33.
Write the balanced chemical equations for the reaction that takes place when zinc, magnesium and sodium react with dilute hydrochloric acid.
Answer:
Reaction of hydrochloric acid (dil.) with Zn, Mg, and Na:
(i) Zn + 2HCl → ZnCl₂ + H₂
(ii) Mg + 2HCl → MgCl₂ + H₂
(iii) 2Na + 2HCl → 2NaCl + H₂

Question 34.
Write two uses of slaked lime.
Answer:
Uses of slaked lime:
(i) It is used in manufacture of bleaching powder.
(ii) It is used as an important building materials

Question 35.
Complete the following equations:
(i) CO₂ + H₂O → ……………..
(ii) CO₂ + 2Na0H → …………….. + ……………..
(iii) SO₂ + H₂O → ……………..
(iv) MgO + H₂SO₄ → …………….. + ……………..
(v) CaC0₃ + 2HCl → …………….. + ……………..
(vi) Na₂O + H₂O → ……………..
(vii) 2NaOH + H₂SO₄ → …………….. + ……………..
(viii) NaOH + HNO₃ → …………….. + ……………..
(ix) CaO + H₂SO₄ → …………….. + ……………..
(x) MgO + 2HCl → ……………..
Answer:
(i) CO₂ + H₂O → H₂CO₃ (carbonic acid)
(ii) CO₂ + 2Na0H → Na₂CO₃ + H₂O (sodium carbonate)
(iii) SO₂ + H₂O → H₂SO₃ (suiphurous acid)
(iv) MgO + H₂SO₄ → MgSO₄ + H₂O (magnesium sulphate)
(v) CaC0₃ + 2HCl → CaCl₂ + H₂O + CO₂ (Calcium Chloride)
(vi) Na₂O + H₂O → 2Na0H (sodium hydroxide)
(vii) 2NaOH + H₂SO₄ → Na₂SO₄ + H₂O (sodium suphate)
(viii) NaOH + HNO₃ → NaNO₃ + H₂O (sodiùm nitrate)
(ix) CaO + H₂SO₄ → CaSO₄ + H₂O (calcium sulphate)
(x) MgO + 2HCl → MgCl₂ +H₂O

Short Answer Type Questions

Question 1.
How can you test the presence of an acid in any substance?
Answer:
Acid can be tested in any substance by the following methods:
(i) Take a drop of the dilute solution of the substance on the tips of your tongue. If tastes sour, it is acidic.
(ii) Dip a blue litmus paper in the solution. If ‘ the colour of the litmus paper turns red, the solution is acidic.

Question 2.
What are organic acids? Give two examples.
Answer:
Soured milk, Lemon, Green mangoes and Karvanda are sour testing. All of them contain some naturally occuring acids. Such acids are also found in humans and plants materials. They are known as organic acids. The acids such as lactic acid, citric acid, tartaric acid and acetic acid are naturally occuring and known as organic acid.

Question 3.
What are the uses of mineral acids in industry?
Answer:
Use of’mineral acids in industry:
(i) Concentration sulphuric acid, nitric acid and hydrochloric acid are used in a large number of metallurgical operations, manufacture of fertilizers and preparations of large number of industrial chemicals.
(ii) Hydrochloric acid is used for removing the deposits from inside the boilers. This process is known as de-scaling.

Question 4.
What are indicators? Name two acid-base indicators.
Answer:
The substances which are used to identify whether a substance is an acid or base is called indicators. For example, litmus solutions give red colour with acids and blue colour with bases. Therefore, litmus is used as indicators. Substances which give different colours with acid and base are called acid-base indicators, for examples. Methyl orange, phenolphthalein.

Question 5.
What are acid salts? Give two examples.
Answer:
The salts which dissolves water to produce a solution, which behaves like an acid is called an acid salt.
Examples: Sodium hydrogen carbonate (NaHCO₃), Potassium hydorgen carbonate (KHCO₃), Sodium hydrogen sulphate etc.

Question 6.
How is potash alum prepared?
Answer:
A mixture of potassium sulphate and aluminium sulphate is dissolved in water and then the solution is concentrated. Potash alum is formed. It separates out as crystals.

Question 7.
Why are sodium bicarbonate and lemon juice used during indigestion?
Answer:
Sodium bicarbonate neutralizes the acidity in the stomach. Hence, it is used during indigestion. Lemon contains acid. It reacts with undigested food and softens it. Thus, lemon is also used in indigestion.

Question 8.
Why are brass vessels coated with tin or kalai?
Answer:
When brass vessels are used to cook food with tamarind or lemon juice, the acids present in it reacts with brass metal and corrode it. The kalai layer protects this vessels from the action of acids. Due to this reason brass vessels are coated with tin.

Question 9.
What is salt? Name any salts and give thier formulae.
Answer:
A substance formed by the neutralisation of an acid with a base is called salt.
Examples:
(i) Potassium nitrate (KNO₃)
(ii) Sodiun: nitrate (NaNO₃)
(iii) Calcium carbonate (CaCO₃)
(iv) Zinc sulphate (ZnSO₄)
(v) Copper sulphate (CuSO₄).

Question 10.
Define an acid. Give three properties of acids.
Answer:
An acid is a substance which when dissolved in water gives hydrogen ions. Examples: H₂SO₄, HNO₃ and HCl etc.
Properties of acids:
(i) They have a sour taste
(ii) They turn blue litmus solution red.
(iii) They have replaceable hydrogen ion.

Question 11.
What are bases? Mention three properties of alkalies.
Answer:
The substance which react with acids to form salt and water only are called bases. Examples: Cu(OH)₂, Fe(OH)₃, Pb(OH)₂ etc.
Properties of alkalies:
(i) They tarn red litmus paper blue
(ii) They have a better taste.
(iii) They turn methyl orange from pink to yellow.

Question 12.
What are the uses of sodium bicarbonate?
Answer:
Uses of sodium bicarbonate:
(i) It is used in medicines to neutralise the acidity in the stomach.
(ii) It is used as backing power.
(iii) It is used in fire extinguisher.

Question 13.
What are the uses of common salt?
Answer:
Uses of common salt:
(i) It is an essential constituents of our diet.
(ii) It is used in the manufacture of soap.
(iii) It is used for glazing pottery. .
(iv) It is a starting material for the manufacture of chlorine, hydrochloric acid, washing soda and sodium hydroxide.
(v) It is used as food preservatives.
(vi) It turns freezing mixture with ice.

Question 14.
Give five uses of potassium nitrate.
Answer:
Uses of potassium nitrate:
(i) It is used in the manufacture of gun powder.
(ii) It is used in making fire works.
(iii) It is used in refrigeration.
(iv) It is used as fertilizers.
(v) It is used in glass industry.

Question 15.
Which acids is called ‘the king of the acids’? Give its uses.
Answer:
Sulphuric acid (H₂SO₄) is called “the king of the acids”.
Uses of sulphuric acid:
(i) It is used in the manufacture of detergents.
(ii) It is used as a dehydrating agent.
(iii) It is used in storage batteries.
(iv) It is used in petrol refining.
(v) It is used in textile, paper and leather industry.
(vi) It is used in fertilizers industry for the manufacture of ammonium sulphate and superphosphate of lime.

Question 16.
Explain with the help of chemical equations how the following acids are formed?
Carbonic acids, Sulphurous acid, Phosphoric acid.
Answer:
(i) Carbonic acid is prepared by dissolving carbon dioxide in water.
CO₂ + H₂O → H₂CO₃ (Carbonic acid)

(ii) Sulphurous acid is formed by dissolving sulphur dioxide in water.
SO₂ + H₂O → H₂SO₃ (Sulphurous acid)

(iii) Phosphoric acid is prepared by dissolving phosphorus pentaoxide in hot water.
P₂O₅ + 3H20 → 2H₃PO₄ (Phosphoric acid)

Acids, Bases and Salts Class 7 HBSE Notes

1. Curd, lemon juice, orange juice and vinegar taste sour. These substances taste sour because they contain acids. The chemical nature of such substances is acidic. The word acid comes from the Latin word acere which means sour. The acids in these substances are natural acids.
2. A substance which produces hydrogen (H⁺) ions when dissolved in water is called an acid. This definition was given by Arrhenius, a Swedish Chemist in 1912.
3. The acids which are prepared from the minerals of the Earth are called mineral acids.
Examples of Mineral Acids

4. The acids which dissolve in water to give a large number of positively charged hydrogen ions are called strong acids.
Examples of Strong Acids : Sulphuric acid, nitric acid, hydrochloric acid and phosphoric acid are examples of strong acids.
5. The acids which dissolve in water to give a small number of positively charged hydrogen ions are called weak acids.
Examples of Weak Acids : Carbonic acid, acetic acid, sulphurous acid, formic acid, etc., are examples of weak acids. In fact, most of the organic acid are weak acids.
6. The acids which contain very little or no amount of water are called concentrated acids.
7. The acids which contain a large amount of water (or solutions of acids in water) are called dilute acids.
8. General Physical Properties of Acids
(i) They have a sour taste.
(ii) They turn blue litmus solution red.
(iii) They turn methyl orange solution pink.
(iv) They do not affect phenolphthalein solution.
(v) Strong acids have a corrosive action on skin. They cause painful blisters.
(vi) Most of the acids are soluble in water.
(vii) Acids solutions are conductors of electricity.
9. Uses of Acids

10. The substances which react with acids to form salt and water as only products are called bases. All oxides of metals are bases. All hydroxides of metals are bases.
11. All bases which are soluble in water are called alkalis.
12. Strong bases completely dissociate in aqueous solution. For example, sodium hydroxide (NaOH), potassium hydroxide (KOH), etc.
13. They undergo partial dissociation in aqueous solution. For example, copper hydroxide Cu(OH)₂, Zinc hydroxide Zn(OH)₂, etc.
14. The bases show the following properties:
(i) These have a bitter taste.
(ii) Bases neither have colour nor small. Only Ammonium hydroxide (NH₄OH) has a pungent smell.
(iii) The basic solutions are soapy to touch, i.e., if little amount of sodium hydroxide is rubbed on fingers, it would give a feeling as if soap has been applied on the fingers.
(iv) Bases turn red litmus blue.
(v) Bases contain hydroxide ions e.g., Sodium hydroxide is represented as NaOH, calcium hydroxide is represented as Ca(OH)₂, etc., where OH is the hydroxy group.
(vi) Bases react with acids to give salt and water.
15. Uses of Bases

16. Special type of substances are used to test whether a substance is acidic or basic. These substances are known as indicators. Turmeric, litmus, china, rose, petals (Gudhal), etc., are some of the naturally occurring indicators.
17. The reaction between an acid and a’base-is known as neutralisation. Salt and water are produced in this process with the evolution of heat.
Acid + Base → Salt + Water (Heat is evolved)
The following reaction is an example :
Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) → Sodium chloride (NaCl) + Water (H₂O)

Haryana State Board HBSE 7th Class Science Solutions Chapter 14 Electric Current and its Effects Textbook Exercise Questions and Answers.

Haryana Board 7th Class Science Solutions Chapter 14 Electric Current and its Effects

HBSE 7th Class Science Electric Current and its Effects Textbook Questions and Answers

Question 1.
Draw in your notebook the symbols to represent the following components of electrical circuits: Connecting wires, Switch in the ‘OFF’ position. Bulb, Cell, Switch in the ‘ON’ position, and Battery.
Answer:
Draw in your notebook the symbols to represent the following components of electrical circuits :
Connecting wires — —
Switch in off position — —
Bulb — —
Cell — —
Switch in ‘on’ position — —
Battery — —

Question 2.
Draw the circuit diagram to represent the circuit shown in Fig. 14.1.
Answer:

Question 3.
Fig 14.2 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.
Answer:

Question 4.
The bulb in the circuit shown in Fig 14.3 does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulbs glow.
Answer:
The problem in this circuit is that of the battery. The cells have not been arranged in right series. The correct circuit is like this.

Question 5.
Name any two effects of electric current.
Answer:
Electric current has following effects:

• Electric current can give rise to heating and lighting.
• Electric current can make a straight conductor a temporary magnet.

Question 6.
When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
Answer:
When current is passed through the wire, it deflects the compass near it from its north-south position behaving like a magnet. This is called magnetic effect of the current. As we know that needle of the compass is made up of a thin magnet, when this needle comes in contact with another magnet the like poles of the magnet repell each other and opposite poles attract each other. So the deflection is seen in the needle. In this case the wire behaves like a magnet and cause deflection in needle of the compass.

Question 7.
Will the compass needle show deflection when the switch in the circuit shown by Fig. 14.4 is closed?

Answer:
No, because there is no source of electric current in this circuit i.e. there is no battery.

Question 8.
Fill in the blanks:
(a) Longer line in the symbol for a cell represents its _______ terminal.
(b) The combination of two or more cells is called a _______.
(c) When current is switched on in a room-heater, its _______.
(d) The safety device based on the heating effect of electric current is called a _______.
Answer:
(a) Positive
(b) Battery
(c) Element becomes red hot and emit heat
(d) Fuse.

Question 9.
Mark ‘T’ if the statement true and ‘F’ if it is false.
(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell.
(b) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks.
(c) An electromagnet does not attract a piece of iron.
(d) An electric bell has an electromagnet.
Answer:
(a) F
(b) T
(c) F
(d) T

Question 10.
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
Answer:
No, the plastic bags do not get attracted by the magnet, so they cannot be separated by an electromagnet. Plastic bags are not magnetic materials, only magnetic materials like iron can be attracted by the magnet.

Question 11.
An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of a wire. Would you agree? Give reasons for your response.
Answer:
No, we would not agree to allow to replace the fuse by a wire. Wires in the fuses are of specific metting points. So we should always use ISI marked fuses in our houses to save short circuits.

Question 12.
Zubeda made an electric circuit using a cell holder shown in Fig. 14.4, a switch and a bulb. When she put the switch in the ‘ON’ position, the bulb did not glow. Help Zubeda in identifying the possible defects in the circuit.
Answer:
It is important to put the cells in right series. The positive terminal of the cell should be connected with negative terminal of the second cell. The switch should be closed properly and bulb should not be fused. If Zubeda will check these then the bulb will certainly glow.

Question 13.
In the circuit shown in Fig. 14.5
(i) Would any of the bulb glow when the switch is in the ‘OFF’ position?
(ii) What will be the order in which the bulbs A, B and C will glow when the switch is moved to the ‘ON’ position?

Answer:
(i) No, bulb will glow.

(ii) The bulb A will glow first, follow by B bulb and then C, because A bulb comes first in the path of electric current flowing from positive terminal towards the negative terminal of the battery.

Extended Learning-Activities and Projects

Question 1.
Set up the circuit shown in Fig. 14.6 again. Move the key to ‘ON’ position and watch carefully in which direction the compass needle gets deflected. Switch ‘OFF’ the current. Now keeping rest of the circuit intact, reverse the connections at the terminal of the cell. Again switch ‘on’ the current. Note the direction in which the needle gets deflected. Think of an explanation.
Answer:
Do it yourself.

Question 2.
Make four electromagnets with 20, 40, 60 and 80 turns. Connect them one by one to a battery of 2 cells. Bring the electromagnet near a box of pins. Count the number of pins attracted by it. Compare the strengths of the electromagnets.
Answer:
Do it yourself.

HBSE 7th Class Science Electric Current and its Effects Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What is electric current?
Answer:
Flow of electrons is called electric current.

Question 2.
What is conventaional current?
Answer:
The current flowing the positive end of the conducting wire towards the negative end is called conventaional current.

Question 3.
What are the different sources of current in an electric circuit?
Answer:
Cell or a battery are the sources of elctric current in an electric circuit.

Question 4.
What role does a switch plays in an electric circuit?
Answer:
The switch regulates the flow of electric current. It allows the current to pass when it is in ‘ON’ position.

Question 5.
Write the symbols of the following : Switch (open).
Switch closed and a cell.
Answer:

Question 6.
What is an open electric circuit?
Answer:
An electric circuit having the switch in ‘off position is called open electric circuit.

Question 7.
What is a closed electric circuit?
Answer:
An electric circuit having the switch in ‘on’ position is called a closed circuit or a complete circuit.

Question 8.
Which effect of the electric current enables the room heater to heat the room?
Answer:
The heating and lighting effect of the electric current enables the room heater to heat the room.

Question 9.
What is a fuse?
Answer:
It is a safety device used to avoid damages from short circuits and over loading in electric appliances.

Question 10.
Which effect of the electric current is used in Electric bells?
Answer:
The magnetic effect of the electric current is used in electric bells to make the sound.

Short Answer Type Questions

Question 1.
What is an electric current and electric circuit?
Answer:
Flow of electrons is called electric current. The path through which the electric current passes is called an electric circuit.

Question 2.
What are the components of the electric circuit? Name different components of the electric circuit and draw their symbols.
Answer:
Various elelments connected in the electric circuit are called components of the electric circuit. Following are some components of electric circuit and their symbols :

Question 3.
What is a cell and what is a battery?
Answer:
Cell and battery are both the sources of electric current in an electric circuit. A cell has two terminals – +ve terminal and – ve terminal. A combination of two or more than two cells is called a battery. Battery is formed by joining a positive terminal of a cell to the negative terminal of other cell.

Question 4.
What is an electric fuse? Explain its working.
Answer:
A fuse is a safety device used in household circuit to prevent damage to electric appliances due to overload and short circuit. It is the weakest part in the electric circuit. It melts and breaks the circuits when the problem arises in the circuit due to short circuiting, overloading or fluctuations of current in power supply system.

Question 5.
What is short circuit and overloaded circuit?
Answer:
Short circuit occurs when live wire and neutral wire come in direct contact. The short circuit occurs either due to melting of plastic insulation or connection of live wire with the earth wire. An overload circuit is the one through which more current passes than it can bear.

Question 6.
What is an M. C. B.?
Answer:
M.C.B. is miniature circuit breaker. This is a safety device like a fuse. It is used instead of or in addition to fuses, in household circuits. It is a switch that automatically switches off a current when it exceeds the specified maximum limit.

Question 7.
Write any three applications of the electromagnets.
Answer:
Fallowing are the applications of the electromagnets :

• Electromagnets are used to separate scrap iron from other metallic scraps.
• Used in electric motors of washing machines, fans, air conditioners etc.
• Used for preparing strong magnets.

Long Answer Type Questions

Question 1.
Explain the construction and working of an electric bell with help of a labelled diagram.
Answer:
An electric bell consists of an electromagnet, Armature, contact spring, Hammer and gong.
Electromagnet: It consists of a U-shaped soft iron rod having insulated copper wire wounded on it. One end of wire is connected to terminal T and other to the brass stud.

Armature: is a soft iron rod, suspended to brass stud. It faces the poles of the electromagnet.

Contact spring is attached to the armature and to a silver-cadmium alloy contact point. Spring is made up of steel.

Contact screw adjustment: It is a brass pillar having a brass screw passing through it. The tip of the screw is made up of silver cadmium alloy. Pillar is connected to T₂ with a copper wire.

Hammer and Gong : Hammer is made up of steel and is attached to the armature. Gong is made up of brass, and the hammer strikes the gong to make the sound.

Working : When electric current passes through T₁ and T₂, current passes from the battery to electromagnet, then to the contact screw and to T₂ completing the circuit. Electromagnet pulls the armature towards itself, the contact spring gets under tension, hammer strikes against gong thus making the sound. The whole process stops, when current stops flowing.

Electric Current and its Effects Class 7 HBSE Notes

• Flow of electrons is called electric current.
• The path in which the electric current flows is called an electric circuit.
• Conventially the current is said to flow from positive end of the conducting wire to the negative end of the conducting wire.
• There are many components which are attached to the path of the electric current. These are called the elements of the electric circuit,
• Elements like cell, battery, switch, bulb, connecting wires are represented by different symbols.
• Cell and battery are the sources of the electric current in a circuit. Battery is the combination of two or more than two cells.
• A circuit is said to be complete or closed when the switch regulating the flow of the current is in ‘on’ position when the switch is in ‘off’ position the circuit is called open.
• Flow of the electric current causes certain effects like heating and lighting and electromagnetism.
• The electric appliances like room heaters, gysers, rods etc. give out heat due to heating effect.
• When electric current passes through a magnetic substance like iron, it behaves like a temporary magnet.
• Electric bell works on this principle.
• Hans Christian Oersted found out the relation between electricity and magnetism.
• A fuse is a safety device used in the household circuits to prevent damage to electric appliances due to overload or short circuits.