# WBBSE Class 8 Geography Solutions Chapter 1 Interior of the Earth

Detailed explanations in West Bengal Board Class 8 Geography Book Solutions Chapter 1 Interior of the Earth offer valuable context and analysis.

## WBBSE Class 8 Geography Chapter 1 Question Answer – Interior of the Earth

Textbook Page no. 1

Question 1.
What lies underneath the hard surface on which we stand?
There are different things lies underneath the hard surface. They are gold mine, coal mine, hat spring volcanoes etc.

Question 2.
Has anybody ever seen the interior of the earth?
It is not possible to see the interior of the carth. But we can somehow feel the warm water of hot spring, gold mine. coal mine and from that we can estitaate a bit what may be in the interior of the earth.

Question 3.
How much one has to dig up to see the centre of the earth?
One has to dig up 6370 km to see the centre of the earth.

Question 4.
How far has it be possible to know the interior of the earth?
It has become possible to guess how is the interior of the earth.

Question 5.
Why does density vary in different layers of the interior of the earth?
The density of substances that lie near the centre more. At the time of the creation of the earth more dense and hot substances accumulate near the centre of the earth due to the gravitational force. Specially iron and nickel rotate around the centre of the earth. Comperatively lighter substances like aluminium and silicon come upword. Generally more we go near the centre of the earth more we feel the pressure extended by the materials. So as the pressure increases the density also increased. Thus the density varies in different layers of the interior of the earth.

Textbook Page no. 2

Question 1.
Why can we not go near the centre of the earth?
It is not possible to dig up 6370 km to go near thic centre of the earth !

Question 2.
Why couid we not collect any information directly about the earth’s interior?
We can not enter in the earth’s interior easily. So it is not possible to collect information about earth’s interior directly.

Textbook Page no. 6

Question 1.
Explain the convection current in asthenosphere with the help of simple experiment.
The layer of asthenosphere is very weak. Substances of this layer are molten and soft in nature. Due to exsessive heat and pressure the rocks are here in a state of viscosity-just like melted asphalt or molasses. Comperatively light materials come upwards when heated geothermally, and allow the heavier one to go downward. Thus the convection current occurs in asthenosphere.

Question 2.
what is the difference between magma and lava?
Magma: Magma is the melted and liquid form of mixture of gas and vapour due to excessive pressure and temperature of earth chamber.
Lava: Lava is the loot molten semiliquid magma that comes out through the opening of earth surface.

Question 3.
You have an idea about the exterior and interior of the earth Which one attracts you more and why?
I like the exterior of the carth as it is possible to be observed and analyzed.

### Class 8 Geography Chapter 1 Question Answer West Bengal Board – Interior of the Earth

Multiple Choice Questions & Answers : (1 mark for each question).

Question 1.
The core of the earth is almost-
i) 3500 km
ii) 5300 km
iii) 6300 km
ii) 3700 km
i) 3500 km.

Question 2.
The average temperature of core is almost-
i) 3000°C
ii) 4060°C
iii) 5000°C
iv) 6000°C
iii) 5000°C.

Question 3.
In between 30-700 km of the mantle is known as-
i) nifesima
ii) crofesima
iii) outer core
iv) inner core
ii) crofesima

Question 4.
Concard discontinuity is lying-
i) above SIAL
ii) below SIM
iii) between SIAL and SIMA
iv) below SIAL
iii) between SIAI, and SIMA

Question 5.
The temperature of mantle is-
i) 1000°-2000°
ii) 3000°-4000°C
iii) ii) 4000°-5000° C
iv) 2000°-3000°
iv) 2000°-3000°C.

Question 6.
The upper layer of the earth’s crust is-
i) SIMA .
ii) SIAL
ii) SIAL.

Question 7.
The outer most part of the earth is very-
i) thick
ii) thin
ii) thin.

Question 8.
Greater part of the earth consists of –
i) Hydrogen
ii) Oxygen
ii) Nitrogen
ii) Oxygen.

Question 9.
The density of the matter near the centre of the earth is-
i) more
ii) less
i) more

Question 10.
The earth originated almost-
i) 640 crore years ago
ii) 540 crore years ago
iii) 460 crore years ago
iii) 460 crore years ago

State wliether True or False : (1 mark for each question)

1. It is an casy task to collect information of earth’s interior.
2. Temperature in carth’s interior increases at the rate of abott 10°C / 33 meters depth.
3. Regarding to the earth’s depth 12 km depth is negligible..
4. Lava comes out through the hot spring.
5. There is a pool of fire in the interior of the carth.
6. Sometimes there are severe treamous due to tremendous cyclone.
7. There are few countries where the electricity is generated from geothermal energy.
8. The volume of the matter increases with the increasing of the temperature.
9. SIAL lies above SIMA or oceanic crust.
10. Conrad discontiunity is lying in between SIAL and SIMA.
11. Greater part of the earth crust consists of Silicon.
12. The rocks of the earth crust is rich in minerals.
13. 47% of earth crust is covered with oxygen.
14. Scientists have found only two layers in the earth interior.
15. Mantle lies below the crust.
1. false
2. false
3. true
4. false
5. true
6. false
7. false
8. true
9. true
10. true
11. false
12. true
13. true
14. fale
15. true.

Fill in the blanks : (1 mark for each question)

1. The earth’s _______ is divided into layers.
2. Scientist have collected information regarding earth’s interior by matching the movement of the _______ .
3. _______ discontinuity line lies in between mantle and core.
4. The _______ encircles the inner core.
5. The two layers composed of different elements and varied density determind by _______.
6. _______ is lying in between SIAL and SIMA.
7. The radius of the earth is _______ km.
8. The distance between earth-surface and the _______ is 6370 km.
9. World’s decpest gold mine located in _______ Africa is only 3-4 km deep.
10. Sometime the earth shakes for tremendous _______ .
11. The earth has been created almost _______ years ago.
12. Hot semi-liquid comes out through the mouth of _______ .
13. Hot spring is found at _______ in West Bengal.
14. _______ is one type of energy.
15. In many countries of the world _______ is genereted from heat energy.
16. _______ lulfils their 30% demand of electircity from geothermal energy.
17. The _______ generates more electricity from geothermal energy in the world.
18. The using of _______ can be reduced by using thermal energy to produce electricity.
19. The average density of the matter is _______ gram / cubic cm near the centre of the earth.
20. In respect of _______ satellites average density of the earth is 5.5 gram / cubic c m.
21. Theof _______ the matter near the centre of the earth is more.
22. _______ matter always precipitates underneath.
23. Light matters _______ upwards.
24. During the origin of the earth the very hot and denser matters move towards the earth’s centre due to _______ pull.
25. Especially ________ and Nickel start rotating the centre of the earth.
26. In general to pressure of _______ increases with the increase of depth towards earth’s interior.
27. Earth’s _____ is divided into layers of varied densities and characteristics.
28. Scientists have collected information regarding earth’s interior by watching the movement of the seismic ______.
29. The average depth of the carth’s crust is ____ km below the occeans and _____ km beneath the continents.
30. _______ lies over the SIMA or ocennic crust.
31. _______ of the crust are rich in various minerals.
32. _______ lies at the top of the crust.
1. interior
2. seismic waves
3. gutenberg
4. Outer core
5. discontinuity line
7. 6700 km
8. core
9. South
10. earth quake
11. 460
12. Volcano
13. Bakreswar
14. Geo-thermal heat
15. electricity
16. Iceland
17, United States of America
18. fossil fuel
19. 11
20. artificial
21. density
22. Heavy
23. float
24. gravitational
25. iron
26. matters
27. interior
28. waves
29. 5 km and 60 km
30. SIAL
31. Rocks
32. Sail.

Match the following : (1 mark for each question)

a) Match the column A with column B.

 Column A Column B a) Moho lies between i) into layers like an onion b) Uppermost layer is compared ii) out of the carth’s interior c) Conrad discontinuity iii) near the surface d) Earth’s interior is divided iv) $5100 \mathrm{~km}$ to $6370 \mathrm{~km}$ deep e) In hot springs boiling water emerges v) the crust aud the mantle f) Lighter elements float upward vi) is between SIAL and SIMA g) The inner core is nearly vii) axis of the earth in semi-solid state h) The outer core rotates around the viii) with the skin of sn apple

a) Moho lies between the crust and the mantle.
b) Uppermost layer is compared with the skin of sn apple.
c) Conrad discontinuity is between SIAL and SIMA.
d) Earth’s interior is divided into layers like an onion.
e) In hot springs boiling water emerges out of the earth’s interior.
f) Lighter elements float upward near the surface.
g) The inner core is nearly 5100 km to 6370 km deep.
h) The outer core rotates around the axis of the earth in semi-solid state.

Very Short Questions & Answers : (1 mark for each question)

Question 1.
What is the radius of the earth?
The radius of the earth is 6370 km.

Question 2.
What is the distance between the surface and the core of the earth?
6370 km. is the distance between the surface and the core of the earth.

Question 3.
What is the depth of the deepest mine of the world?
The depth of the deepest mine of the world 3-4 km.

Question 4.
What is the rate of increasing temperature in the earth’s interior?
The temperature in the earth’s interior increases at the rate of about 1°C / 33 meters depth,

Question 5.
Which is the artificial deepest hole of the world?
The artificial deepest hole of the world is the hole in kala peninsula of north western Russia measuring a depth of 12 km.

Question 6.
What comes out from the hot spring?
Hot water comes out from the hot spring.

Question 7.
What comes out form the mouth of the volcanoes?
Hot molten semi-liquid lava comes out from the mouth of the volcano.

Question 8.
When was the earth created?
The earth was created almost 460 crore years ago.

Question 9.
What sappens to the matter if the temperature is increased?
On heating the solid matter converts into liquid and expands in volume.

Question 10.
Where in the earth the temperature and the pressure both are excessive?
in the interior of the earth.

Question 11.
Where in West Bengal hot spring is situated?
Hot spring is situated at Bakreswar of West Bengal.

Question 12.
What is called this type of water?
This type of water is called ground water.

Question 13.
What is geo-thermal heat?
Geo-thermal heat is one type of energy.

Question 14.
What can be generate from geo-thermal energy?
Electricity can be generated from geo-thermal energy.

Question 15.
What percent of the demand of electricity is fulfilled from geo-thermal energy in Ireland?
Almost 30%.

Question 16.
Which country of the world uses most amount of geo-thermal energy to generate electricity?
The United States of America.

Question 17.
The use of which substance can be reduced by generating electricity by using geo-thermal energy?
The use of fossil fuel can be reduced.

Question 18.
What is the average density of earth crust?
Only 2.6 to 3.3 gram / cubic cm.

Question 19.
What is the average density of matter near the centre of the earth?
it Answer: Almost 11 gram / cubic cm.

Question 20.
What is the average density of earth in respect of artificial satellites?
5.5 gram / cubic cm.

Question 21.
Which wave can not pass through liquid or semi liquid medium?
S wave can not pass through liquid or semi liquid medium.

Question 22.
What is increased with the increasing of pressure on the matter?
Density increases.

Question 23.
Which layer of earth is present just below the earth crust?
Mantle is present just below the earth crust.

Question 24.
Who wrote the famous science fiction of earth?
Jule Verne.

Question 25.
Where is the layer SIMA situated?
SIMA situated beneath the ocean.

Question 26.
What does SIMA consist of ?
The layer SIMA consists of Silicon (Si) and Magnesium (Mg).

Question 27.
What the SIMA made up of?
It is made up of basalt like ignious rock.

Question 28.
Where is the layer SIAL situated?
SIAL is situated above SIMA.

Question 29.
What is the uppermost layer of the eartherust?
The uppermost layer of the earthcrust is Soil.

Question 30.
Which gas is present covering most of the part of earth crust?
Oxygen.

Question 31.
What is the second element of earth crust?
Silicon is the second element of earth crust.

Question 32.
Which line seperates the two different elements and density layers?
Discontinuity line.

Question 33.
Which line presents in between SIAL and SIMA?

Question 34.
What is the temperature of mantle?
2000°-3000°C.

Question 35.
W ist are the tnain elements of mantle?
Nickel Ctromium, Magnesium and Silicon.

Question 36.
What is the meaning of the word asthenosphere?
weaker layer.

Question 37.
How thick is the core?
The core is 3500 km. thick.

Question 38.
What is the average temperature of the core?
Almost 5600°C.

Question 39.
What is the density of core?
Almost 9.1 to 13.1 gram / cubic cm.

Question 40.
What is the depth of inner core?
5100 km to almost 6370 km.

Question 41.
What is the depth of outer core?
2900 km to almost 5100 km.

Question 42.
Which line present between the mantle and the core?
Gutenberg discontinuity.

Short Questions & Answers : (2 marks for each question)

Question 1.
What is magma?
Due to enormous pressure and temperature the substances of the earth’s interior remain liquid, being mixed with gas and vapour is called magma.

Question 2.
What is lava?
When hot molten magma of the earth’s interior, comes out through the cracks and joints on the earth’s surface, it is called lava.

Question 3.
In what state the mattrers remain if the pressure and temperature both are excessive in the interior of the earth?
If the temperature in the interior of the earth increases the matter melts into liquid and expands in volume. On the other hand with the increasing of the pressure the volume decreases.

Question 4.
What is Geo-thermal energy?
Geo-thermal heat is one type of energy. The heat of the earth gradually transferred to the earth crust. This heat is ealled Geo-thermal energy.

Question 5.
What is density?
Density is the measure of mass present in unit voiume of substance.

Question 6.
What is the Earth core?
The innermost layer of the carth lies encircles the centre of the earth is known as the Earth core.

Question 7.
What is a NIFE?
The layer of the mantle that made up of Nickel and Ferrum is known as NIFE.

Question 8.
How is the Earth core divided?
The Earth core is divided into two parts (i) inner core and (ii) outer core.

Long Questions & Answers : (3 marks for each question)

Question 1.
What is Seismic waves?
The scientists have collect information about the earth interior by watching the movement of the seismic wave. The seismic wave passes through different substances. Sometimes it is rapid sometimes it is slow. There are two types of waves. One is P and another is S. P wave can pass through either solid or liquid. But S wave can not pass through liquid or semi-liquid materials.

Question 2.
What do you know by the term ‘Inner core’?