GSEB Solutions Class 8 Social Science Chapter 2 What is Around Us?

Gujarat Board GSEB Solutions Class 8 Social Science Chapter 2 What is Around Us? Textbook Exercise Important Questions and Answers, Notes Pdf.

Gujarat Board Textbook Solutions Class 8 Social Science Chapter 2 What is Around Us?

GSEB Class 8 Social Science What is Around Us? Textbook Questions and Answers

Answer the following questions:
Question 1.
What do you know about our Earth ? Write a short note.
Answer:
Our Earth is a member of the solar system. – Among all the members of the solar system, only Earth x has got suitable temperature, air and water required to sustain life. Earth was a huge ball of fire which cooled down with time. Various elements on Earth were transformed into solids, liquids, gases or life forms in the process.
They formed the four major spheres on Earth, which are :

1. Lithosphere,
2. Hydrosphere,
3. Atmosphere and
4. Biosphere.

Question 2.
How much time was taken by the Earth to reach its present form after being detached from the Sun? Why?
Answer:
It is believed that the Earth was a part of the Sun. It got detached from the Sun due to a collision. So Earth was a huge ball of fire and then it cooled down with time. It took millions of years to cool down. Even though modern science has progressed very much, it is still not confirmed as to how much time Earth took to reach its present state.

Question 3.
How are the spheres of Earth interrelated?
Answer:
All the four spheres on Earth, i.e., lithosphere, hydrosphere, atmosphere and biosphere are interrelated very closely. Due to the collective impact of all these spheres conditions favourable for life have developed on Earth.

Lithosphere is useful in many ways. It is the home of”‘ mankind. It gives space for constructing homes, obtaining fresh water and land for cultivation as well as forests and useful minerals for industries. Hydrosphere provides fresh water to all living organisms. Atmosphere provides life giving oxygen to all living organisms. No life form can survive without air and water.

That part of the lithosphere, hydrosphere and atmosphere where the living world exists is called ‘Biosphere’. This is one of the important spheres on Earth as this is the only planet in the solar system that has the biosphere. Thus all four spheres are interrelated.

Fill in the blanks with appropriate words:

1. There are totally …………………. spheres on the Earth.
Answer:
four

2. Lithosphere covers approximately …………………. per cent of the surface of the Earth.
Answer:
29

3. The most prominent liquid component in the atmosphere is ………… .
Answer:
water

4. Hydrosphere which is made of water, makes per cent of the surface of Earth.
Answer:
71

5. …………………. gas absorbs the ultra-violet rays of the sun.
Answer:
Ozone

Give the meaning of the following terms:
(1) Lithosphere
(2) Hydrosphere
(3) Atmosphere
(4) Biosphere
(5) Pollution
Answer:
(1) Lithosphere : The solid part on which we live is known as the lithosphere. ‘Litho’ means ‘Rock’ and , ‘Sphere’ means ‘layer’. This layer occupies about 29% of ‘ the surface of the Earth and is almost 64 km to 100 km thick. Landforms like mountains, plateaus, plains, valleys, etc. are seen on the lithosphere.

(2) Hydrosphere : The liquid component of Earth is > called ‘Hydrosphere*. It includes oceans, seas, bays, straits, lakes, ponds, rivers, etc. The hydrosphere covers about 71 % of the Earth’s surface.

(3) Atmosphere : The sphere of air that wraps the Earth from all sides is called ‘Atmosphere*. It extends up to about 1600 km from the surface of the Earth\ \ and it cannot be seen clearly with the naked eye. Various gases, water vapour, dust particles, smoke, salt particles, micro-organisms, etc. make up the atmosphere, which is colourless, odourless and transparent.

(4) Biosphere: That part of the lithosphere, hydrosphere and atmosphere where the living world exists is called ‘Biosphere. This is one of the important spheres on Earth as this is the only planet in the solar system that has the biosphere. Biosphere includes human beings, animals, vegetation and minute insects.

(5) Pollution : The process wherein land, water, air, etc. which are necessary components for life, are degraded ”Ss is called ‘Pollution’.

State whether the following statements are true or false:

1. The Earth is a member of the solar family.
Answer:
True

2. The proportion of water on the surface of Earth is less than the proportion of land.
Answer:
False

3. The fresh water is a gift of hydrosphere.
Answer:
True

4. Oxygen reduces the intensity of nitrogen.
Answer:
False

Explain how the following are related to your life:
1. Mountains
2. Fields:
3. Rivers:
4. Lakes:
5. Forests:
Answer:
1. Mountains : (1) Mountains obstruct moisture bearing winds and bring rainfall to one side while the other side gets less rainfall. Mountains are homes to beautiful hill stations that are places of tourist interest. Rivers originating from mountains form fertile plains, and. also provide fresh water to us.

2. Fields: Various crops like grains, cash crops, oil seeds, etc. are cultivated in various kinds of fields. Fertile fields provide mankind with food that is very necessary to sustain life.

3. Rivers: Rivers are like our mothers. They provide water for drinking as well as for irrigation. Fresh water of rivers is useful in many ways.

4. Lakes: Lakes and ponds supply water for drinking as well as for irrigation. Larger reservoirs are also useful as transport routes.

5. Forests:

1. 1. Forests prevent the climate from becoming dry and unfavourable. Forests keep the weather cool and help to bring rains.
   2. Forests obstruct winds and thus protect crops as well as arrest the growth of deserts.
   3. Wood available from forests is used for building houses, making furniture and fuel.
   4. Forests provide raw material for many industries.

Activities

(1) Draw the picture of the spheres of the Earth given on page no. 6 of your textbook.
(2) Locate using various colours oceans, seas, bays, lakes, straits, gulfs, etc. on the out-lined map of the world.
(3) Make a list of natural events and human activities that have adversely affected various spheres of the Earth.
(4) Find out the resources of pollution in you surrounding and study their effects as well as suggest solutions to eradicate it.

GSEB Class 8 Social Science What is Around Us? Intext Questions and Answers

Question 1.
What would happen if there were no seas?
Answer:
Fresh water is necessary to living organisms. Rain is the main source of fresh water. Rainwater comes from oceans only. If oceans were not there, there would be no rain. Without rain, we would not get fresh water to drink. Without water, the life on the earth cannot – survive. Thus, we cannot think of life without oceans.

Question 2.
On the basis of which experiences can you state that Atmosphere exists on the surface of Barth?
Answer:
On the basis of the following experiences, we can say that Atmosphere exists on the surface of Earth:

1. We can feel air moving due to wind. We shiver due to cold winds in winter. The hot air in summer burns our skin.
2. Growth of various life forms like plants and animals signifies the presence of air and moisture.
3. Presence of dust and smoke which can be seen floating in air are responsible for dispersal of – sunlight and various diseases respectively.

Question 3.
If any element in the living world is destroyed, then what will be its effect on our lives? For instance, what would happen if birds were wiped out from the face of Earth?
Answer:
Birds eat insects which damage crops. If birds would become extinct, then insects would destroy all the crops.

GSEB Class 8 Social Science What is Around Us? Additional Important Questions and Answers

Choose the correct alternative from those given below each question:

Question 1.
How many spheres does Earth have ?
A. Two
B. Four
C. Three
D. Five
Answer:
B. Four

Question 2.
How much surface area does the lithosphere occupy ?
A. 98 %
B. 97 %
C. 71 %
D. 29 %
Answer:
D. 29 %

Question 3.
Which sphere of Earth cannot be seen ?
A. Lithosphere
B. Biosphere
C. Atmosphere
D. Hydrosphere
Answer:
C. Atmosphere

Question 4.
Which sphere of Earth has neither colour nor taste or smell ?
A. Hydrosphere
B. Atmosphere
C. Biosphere
D. Lithosphere
Answer:
B. Atmosphere

Question 5.
Which is the main source of fresh water ?
A. Rivers
B. Lakes
C. Wells
D. Rain
Answer:
D. Rain

Question 6.
How much surface area does hydrosphere cover ?
A. 71 %
B. 97 %
C. 68 %
D. 78 %
Answer:
A. 71 %

Question 7.
How deep are ocean trenches ?
A. 8 to 9 km
B. 10 to 11 km
C. 5 to 6 km
D. 14 to 15 km
Answer:
B. 10 to 11 km

Question 8.
How much of Earth’s total water is in the oceans ?
A. 71 %
B. 78 %
C. 80 %
D. 97 %
Answer:
D. 97 %

Question 9.
Up to how many kilometres above the surface does atmosphere extend?
A. 1600
B. 1000
C. 1200
D. 1400
Answer:
A. 1600

Question 10.
What is the proportion of nitrogen in atmosphere?
A. 71 %
B. 48 %
C. 78 %
D. 21 %
Answer:
C. 78 %

Question 11.
What is the proportion of oxygen in atmosphere ?
A. 21%
B. 48%
C. 78%
D. 25 %
Answer:
A. 21%

Question 12.
Which atmospheric gas prevents ultra-violet rays of the Sun from reaching Earth ?
A. Nitrogen
B. Oxygen
C. Ozone
D. Hydrogen
Answer:
C. Ozone

Question 13.
Which atmospheric gas reduces the intensity of oxygen?
A. Ozone
B. Carbon dioxide
C. Nitrogen
D. Hydrogen
Answer:
C. Nitrogen

Question 14.
Which component of atmosphere spreads sunrays in all directions?
A. Oxygen
B. Ozone
C. Carbon dioxide
D. Dust particles
Answer:
D. Dust particles

Question 15.
Which gas increases in volume in areas of heavy vehicular traffic ?
A. Carbon monoxide
B. Nitrogen
C. Hydrogen
D. Argon
Answer:
A. Carbon monoxide

Question 16.
Which gas causes global’ warming when increased in volume ?
A. O₂
B. H₂
C. N₂
D. CO₂
Answer:
D. CO₂

Fill in the blanks with proper words or numbers:

1. In the solar system, only …………………. has favourable temperature, water and air to sustain life.
Answer:
Earth

2. The Earth was a huge ball of ………………….. at the time of its origin.
Answer:
fire

3. The lithosphere is composed of ………………….. and …………….. .
Answer:
rocks, soil

4. ………………… and ……………………. gases of the atmosphere sustain life on Earth.
Answer:
Oxygen, nitrogen

5. ………………. gas in the atmosphere reduces the intensity of oxygen.
Answer:
Nitrogen

State whether the following statements are true or false:

1. As we go higher from the surface of Earth the volume of most gases reduces.
Answer:
True

2. Carbon dioxide is found more in the lower layer of air.
Answer:
True

3. Sound can be heard only due to atmosphere.
Answer:
True

4. Only Earth, a planet of the solar system, has biosphere.
Answer:
True

5. The amount of CO₂ decreases due to cutting of trees.
Answer:
False

Match the pairs correctly:

Section ‘A’	Section ‘B’
(1) Lithosphere	(1) Sphere of various gases
(2) Atmosphere	(2) Base of life sustainability
(3) Biosphere	(3) Combination of four spheres
	(4) Residence of all living organisms including humans

Answer:
(1 – 4), (2 – 1), (3 – 2).

Answer the following questions in one or two sentences :

Question 1.
What is the characteristic of the Earth as a member of the solar system?
Answer:
Among all the members of the solar system, only Earth has got suitable temperature, air and water required to sustain life.

Question 2.
Which are the major spheres on Earth ?
Answer:
There are four major spheres on Earth. They are :

1. Lithosphere
2. Hydrosphere
3. Atmosphere and
4. Biosphere.

Question 3.
What is Magma ?
Answer:
Molten rocks in the interior of Earth are known as ‘Magma’.

Question 4.
Why is the crust of Earth not broken ?
Answer:
There are many gases present in the interior of the Earth which rise up with pressure and heat. But the pressure of rocks on the surface of Earth is equally strong. Thus a balance is maintained between the two and the crust of the earth does not break.

Question 5.
Name the oceans on Earth.
Answer:
There are four oceans on Earth: They are the Pacific, the Atlantic, the Indian and the Arctic oceans.

Question 6.
Which elements make up atmosphere ?
Answer:
Atmosphere is made up of various gases, water vapour, dust particles, salt particles, smoke, microorganisms, etc.

Question 7.
Which gases make up atmosphere ?
Answer:
Atmosphere is composed of gases like nitrogen, oxygen, carbon dioxide, hydrogen, ozone, etc.

Question 8.
How does ozone gas work ?
Answer:
Ozone gas absorbs ultra-violet sunrays and saves the biosphere on Earth from their harmful effects.

Question 9.
Where and when is ozone gas found in greater proportion ?
Answer:
Ozone gas is found in greater proportion in the morning in open grounds and in the air near the sea.

Question 10.
What is meant by ‘Condensation’?
Answer:
The process of cooling of vapour is called „ ‘Condensation’. Various forms of moisture like dew, fog, clouds and precipitation, etc. are seen due to condensation.

Question 11.
How are dust particles in the atmosphere useful?
Answer:
Dust particles in the atmosphere spread sunlight in all directions. It is due to these particles that it does not suddenly turn dark after sunset and neither does it ‘ suddenly turn bright after sunrise.

Question 12.
Why are radio and television transmissions possible ?
Answer:
Sound is heard only in the presence of atmosphere. “Radio and television transmissions are possible only due to atmosphere.

Question 13.
What are the divisions of biosphere? What do they include?
Answer:
There are two main divisions of biosphere : Living (Biotic) and Non-living (Abiotic). The biotic division includes human beings, vegetation, animals and minute insects. The lithosphere, hydrosphere and atmosphere are included in the abiotic division.

Question 14.
Which human activities affect the lithosphere adversely ?
Answer:
Human activities like intense mining for minerals, underground nuclear testing, deep drilling to obtain mineral oil and tube wells etc. affect the lithosphere adversely.

Answer the following questions:

Question 1.
How did the four spheres come into existence on Earth?
Answer:
Earth was a huge ball of fire which cooled down with time. Various elements on Earth were transformed into solids, liquids, gases or life forms in the process. They formed the four major spheres on Earth, which are : (1) Lithosphere, (2) Hydrosphere, (3) Atmosphere and (4) Biosphere. The elements on the surface of the Earth that got transformed into solid (land) make up the ‘Lithosphere’. Elements that got transformed into liquid form the ‘Hydrosphere’; those which transformed into gases are called the ‘Atmosphere’ and the living world which developed is known as the ‘Biosphere’.

Question 2.
Explain the importance of lithosphere.
Answer:
Importance of lithosphere: The solid part on which we live is known as the lithosphere. ‘Litho’ means ‘Rock’ and ‘Sphere’ means ‘layer’. This layer occupies about 29 % of the surface of the Earth and is almost 64 km to 100 km thick. Landforms like mountains, plateaus, plains, valleys, etc. are seen on the lithosphere.

Lithosphere is useful in many ways. It is the home of mankind. It gives space for constructing homes, obtaining fresh water and land for cultivation as well as forests and useful minerals for industries.

Question 3.
State the uses of hydrosphere.
Answer:
The liquid component of Earth is called ‘Hydrosphere*. It includes oceans, seas, bays, straits, lakes, ponds, rivers, etc. The hydrosphere covers about 71 % of the Earth’s surface.
Uses of hydrosphere :

1. Hydrosphere provides us with fresh water.
2. Most of the rainwater comes from hydrosphere.
3. Valuable chemicals and minerals are obtained from seas and oceans.
4. A variety of aquatic life is sustained by oceans and seas.
5. Salt is produced from sea water.
6. The tremendous force of waves, tides and ocean currents is a potential source for generating electricity.
7. Oceans are also useful as waterways.

Question 4.
State the uses of atmosphere.
Answer:
The sphere of air that wraps the Earth from all sides is called ‘Atmosphere*. It extends up to about 1600 km from the surface ot the Earth and it cannot be seen clearly with the naked eye.

Uses of atmosphere :

• Oxygen in the atmosphere is essential to all living organisms on the earth.
• Nitrogen is necessary for the growth of vegetation.
• Carbon dioxide is the food for green vegetation.
• Nitrogen reduces the intensity of oxygen.
• Ozone gas absorbs the ultra-violet sunrays and thus protects the earth from the intense heat’ of the sun. Ozone is also an invigorating gas.
• The dust particles in the atmosphere help to spread sunrays in all directions. So there is neither sudden light after sunrise nor sudden darkness after sunset. Dust particles reflect sunrays which help us to receive sunlight. These particles also help to form clouds.
• We can hear sound only due to the atmosphere. Radio broadcasts and television are possible only due to the presence of atmosphere.

Question 5.
Which human activities affect the hydrosphere adversely ?
Answer:

1. Oil spills from ships and
2. Disposal of industrial and chemical waste into rivers, streams, ponds, lakes and seas pollutes the water and destroys marine life. This is highly dangerous for the hydrosphere.
3. Polar ice caps have started melting due to increasing heat.

Question 6.
Which human activities pollute the atmosphere and what are the effects?
Answer:
The balance of the various spheres of Earth has been disturbed due to activities undertaken (knowingly or unknowingly) by humans for their own development. Activities like nuclear testing, excessive drilling for mineral oil or tubewells, dumping of waste, releasing smoke from factories and exhaust from vehicles, etc. pollute all the spheres surrounding Earth.

Due to increase in heat around Earth, the Polar caps have started melting, rain has been affected adversely due to thoughtless cutting of trees. All these activities affect the biosphere.

Volume of carbon dioxide (CO₂) has increased in the atmosphere and hence there is increase in global warmin

Write short notes :

Question 1.
Lithosphere
Answer:
The solid part on which we live is known as : -the lithosphere. ‘Litho’ means ‘Rock’ and ‘Sphere’ means ‘layer’. This layer occupies about 29 % of the surface of the Earth and is almost 64 km to 100 km thick. Landforms like mountains, plateaus, plains, valleys, etc. are seen on the lithosphere. As we move towards the centre of the Earth, the temperature increases. Rocks in the interior of the Earth which are in molten state are known as ‘Magma’.

Many gases present in the interior rise up due to pressure and heat. But the pressure of rocks on Earth’s surface is equally strong. Thus a balance is maintained and the Earth’s crust does not break. However, if this balance is disturbed the crust breaks and a volcano erupts. Lithosphere is useful in many ways. It : is the home of mankind. It gives space for constructing homes, obtaining fresh water and land for cultivation as ( well as forests and useful minerals for industries.

Question 2.
Hydrosphere
Answer:
The liquid component of Earth is called I ‘Hydrosphere’. It includes oceans, seas, bays, straits,
lakes, ponds, rivers, etc. The hydrosphere covers about 71 % of the Earth’s surface. A water body that carries huge amount of water is known as an ‘Ocean’. Pacific, Atlantic, Indian and Arctic are the four oceans on Earth and they are connected to each other. These oceans are huge and deep and have valleys which are as deep as 10 to 11 km at their bottom. Ocean beds have features similar to that of the Earth’s surface with mountains, plateaus, vast plains, valleys, etc.

Oceans contain about 97 % of water on Earth and about l/3rd of remaining water is trapped in ice-caps and glaciers. Only some water is accumulated in lakes, while some flows into rivers and some is stored in the interior of the Earth as ground water. The amount of potable water (water fit for drinking) or fresh water is very less. Fresh water beings precious should be used with care and should not be wasted. Life cannot be sustained without fresh drinking water. Moisture for rain, which is the main source of fresh water, comes from oceans. Valuable chemicals, fish, salt, minerals, etc. are obtained from seas and oceans. ‘ A large variety of aquatic life is sustained in oceans and seas. The tremendous force of waves, tides and ocean currents is a potential source for generating electricity. Oceans are also useful as waterways.

Question 3.
Atmosphere
Answer:
The sphere of air that wraps the Earth from all sides is called ‘Atmosphere’. It extends up to about 1600 km from the surface of the Earth and it cannot be seen clearly with the naked eye. Various gases like nitrogen, N oxygen, carbon dioxide, ozone, hydrogen, water vapour, dust particles, smoke, salt particles, micro-organisms, etc. make up the atmosphere, which is colourless, odourless and transparent. Atmosphere contains about 78 % nitrogen, 21 % of oxygen, and 1 % other gases. As we go higher from the surface of the Earth, the amount of these gases decreases. Carbon dioxide being heavy is found more , in the lower layer of air.

Ozone gas comprises a small proportion of air. This gas absorbs the ultra-violet rays of the Sun thus protecting the Earth from excessive heat of the Sun. This gas is more in proportion in the morning in open grounds or areas near the sea. Oxygen and nitrogen gases sustain life on Earth. Nitrogen reduces the intensity of oxygen. The most important component of atmosphere is water. Water evaporates due to heat and stays in the atmosphere in the form of water vapour. The process of cooling of vapour is called ‘Condensation’. Various forms – of moisture-dew, fog, clouds and precipitation are seen due to condensation.

Atmosphere affects all aspects of human life such as food habits, clothing, habitat, colour, economic activities, etc. The dust particles in the atmosphere prove that sunrays spread in all directions. It is due to dust particles that it does not suddenly turn dark after sunset and does not suddenly turn bright after sunrise. Dust . particles reflect sunrays onto the Earth’s surface and we receive sunlight. Sound is heard only in the presence of atmosphere. Radio broadcasts and television are possible only due to atmosphere.

Question 4.
Biosphere
Answer:
That part of the lithosphere, hydrosphere and atmosphere where the living world exists is called ‘Biosphere’. This is one of the important spheres on Earth as this is the only planet in the solar system that has the biosphere. Biosphere includes human beings, animals, i vegetation and minute insects. Human life is dependent on biosphere as we obtain food and many other necessary things from biosphere. We cannot live without vegetation or animals; hence biosphere is the base of our existence. Biosphere is divided into :

1. Non-living (Abiotic) and
2. Living (Biotic). The non-living or abiotic division includes lithosphere, hydrosphere and atmosphere. The Living or biotic division includes micro-organisms, plants and animals.