1
What do you understand by lithosphere?
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Earth's outer shell of crystalline surface rock, ranging from 6 to 48 km in thickness from oceanic crust to mountain ranges is known as lithosphere.
Earth's Structure
ICSE Class 9 Geography · Solutions for Goyal Brothers Prakashan Geography by Veena Bhargava Class 9 ICSE · 40 solved questions
2
Name the two layers of lithosphere.
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The two layers of lithosphere are:
- Sial
- Sima
3
What do you understand by mantle?
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It is the layer of silicate rock between the crust and the outer core. The depth of Mantle varies between 35 to 2900 km. It consists of dense and rigid rocks containing magnesium and iron. The Mantle is divided into two parts:
- the Upper Mantle or Asthenosphere
- the Lower Mantle or the Mesosphere
4
What is the position of mantle in the Earth?
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The mantle layer lies between the crust and the core of earth. Its upper boundary is marked by Mohorovicic Discontinuity and its lower boundary is marked by the Gutenburg Discontinuity.
5
What is core? By what other name is it known as?
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The central part of earth that probably consists of dense nickel and iron alloy (Nife) is known as core. It is also known as Barysphere. It's temperature is estimated to be about 2700°C.
6
State the composition of the SIAL layer.
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SIAL layer consists of Silica and Aluminium.
7
State the properties of the core of the Earth.
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The properties of the core of the Earth are:
- It consists of Nickel and Iron with a temperature estimated to be 2700°C.
- The inner core also consists of nickel and iron and is forced into a solid state by increased pressure.
8
What is Earth’s crust composed of?
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The earth's crust consists of two layers - SIAL and SIMA.
The material of the upper or continental part of the earth's crust, characterized by relatively low density is called the SIAL layer.The SIAL layer has predominance of Silica and Aluminium. It is also known as granite layer which floats on SIMA.
The lowest layer of the earth's outer crust that underlies the SIAL is SIMA layer. It consists of Silica and Magnesium and it is also known as basaltic layer.
9
What does 'Nife' mean?
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'Nife' is the name given to the core of the Earth as it is rich in Nickel and Ferrous(iron) alloy.
10
Why does the temperature increase as we go down(underground)?
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High pressure in the interior of the earth exercises a powerful influence on the temperature and physical state of the earth. The temperature of the earth's interior goes on increasing at the rate of 1°c for every 32 metres. Thus, the temperature increase as we go down(underground).
11
How does Sial differ from Sima?
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| S. No. | Sial | Sima |
|---|---|---|
| 1. | This is the uppermost layer of the earth's crust. | This is below the Sial layer. |
| 2. | Its thickness is nearly 20 km. | Its average thickness is about 25 to 30 km. |
| 3. | It is composed of Silica(Si) and Aluminium(Al). | It is composed of Silica(Si) and Magnesium(Mg). |
| 4. | It is not a continuous layer. It is not found on ocean basin. | It is a continuous layer. |
| 5. | It is less dense. | It is more dense. |
| 6. | It is Granite layer. | It is Basaltic layer. |
12
Name the two most important and abundant chemical elements present in the Earth's crust.
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The two most important and abundant chemical elements present in the Earth's crust are Silica and Oxygen.
13
What is meant by Mohorovicic Discontinuity?
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The contact zone of the Crust and Mantle is called Mohorovicic Discontinuity.
14
What is mantle composed of?
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The Mantle layer is composed of magnesium and iron silicates, along with substantial quantities of sulphides in the upper mantle and nickel and iron in the lower mantle.
1
Crust
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Earth's outer shell of crystalline surface rock, ranging from 4 to 48 km in thickness from oceanic crust to mountain ranges is called Crust.
2
Mantle
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The layer of Iron and Magnesium silicate rock and nickel and iron alloy between the crust and the outer core with depth varying from 35 to 2900 km is called Mantle.
3
Core
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The central part of earth that probably consists of dense nickel and iron alloy is known as core.
4
Nife
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The core of earth consists of nickel and iron alloy and is known as Nife.
1
Crust and Core
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| S. No. | Crust | Core |
|---|---|---|
| 1. | The crust is the outermost layer of the earth. | The core is the innermost layer of the earth. |
| 2. | Crust is about 60 km thick below high mountains and just 5-10 km below the oceans. | Core is about 7000 km in diameter. |
| 3. | Crust has relatively low temperatures. | Core has very high temperature ranging from 4400°C to about 6000°C. |
| 4. | Crust is inhabited by living organisms. | Core is uninhabitable. |
2
Sial and Sima
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| S. No. | Sial | Sima |
|---|---|---|
| 1. | This is the uppermost layer of the earth's crust. | This is below the Sial layer. |
| 2. | Its thickness is nearly 20 km. | Its average thickness is about 25 to 30 km. |
| 3. | It is composed of Silica(Si) and Aluminium(Al). | It is composed of Silica(Si) and Magnesium(mg). |
| 4. | It is not a continuous layer. It is not found on ocean basin. | It is a continuous layer. |
| 5. | It is less dense. | It is more dense. |
| 6. | It is Granite layer. | It is Basaltic layer. |
1
Draw a self-explanatory diagram showing the composition and structure of the Earth.
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Below diagram shows the composition and structure of the Earth:
1
What is the rate of change of temperature inside the earth?
- (a)Temperature decreases at the rate of 1°C for every 32 metres of descent.
- (b)Temperature increases at the rate of 1°C for every 32 metres of descent.
- (c)Temperature remains constant
- (d)Temperature decreases at the rate of 32°C for every 1 metre of descent.
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Temperature increases at the rate of 1°C for every 32 metres of descent.
2
Sial is the part of ............... .
- (a)Mantle
- (b)Core
- (c)Crust
- (d)Sima
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Crust
3
Sima is composed of ............... & ...............
- (a)Silica & Aluminium
- (b)Silica & Nickel
- (c)Silica & Magnesium
- (d)Silica & Ferrous
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Silica & Magnesium
4
Gutenburg Discontinuity separates ............... & ...............
- (a)Crust & Core
- (b)Core & Mantle
- (c)Mantle & crust
- (d)Sial & Sima
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Core & Mantle
5
Mesosphere is another name of ............... .
- (a)Crust
- (b)Core
- (c)Mantle
- (d)Sima
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Mantle
6
Asthenosphere remains in ............... state.
- (a)Liquid
- (b)Molten
- (c)Partially Molten
- (d)Solid
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Partially Molten
7
Gutenburg Discontinuity is placed at ............... km depth from the surface.
- (a)3270
- (b)2900
- (c)32
- (d)1000
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2900
8
Which of the following layer is also called Barysphere?
- (a)Mantle
- (b)Asthenosphere
- (c)Core
- (d)Continental crust
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Core
9
Inner core is solid due to
- (a)high temperature
- (b)high pressure
- (c)high density
- (d)low pressure
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high pressure
10
Which of the following rocks and mineral composition is correct for Continental crust?
- (a)Basalt, Si, Al.
- (b)Granite, Si, Ma.
- (c)Granite, Si, Al.
- (d)Basalt, Granite, Si, Ma.
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Granite, Si, Al.
11
The average density of earth expressed in g/cm3 is
- (a)5.5
- (b)2.7
- (c)11
- (d)4.3
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5.5
12
Which of the following discontinuity is found between crust & mantle?
- (a)Conrad
- (b)Gutenberg
- (c)Mohorovicic
- (d)Lehmann
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Mohorovicic
1
Core is called Nife.
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The core of the Earth is also called 'Nife' as it is rich in Nickel and Ferrous(iron) alloy.
2
Inner core is solid although the temperature is high.
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The inner core of the earth is forced into a solid state by increased pressure, that is three million tonnes greater at the center of the earth than at the surface.
3
Core is working as a magnetic field.
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The Earth’s core, especially the outer core, is made up of molten iron and nickel. Due to the rotation of the Earth, these liquid metals move and generate electric currents. This movement of electrically charged fluid produces a magnetic field around the Earth.
This phenomenon is called the dynamo effect, and it is the reason why the Earth behaves like a giant magnet, with a North and South Magnetic Pole.
1
People living in Japan often are witnessed of hot fiery material comes out from the earths inside during volcanism. What is the reason that the material which comes out from inside the earth is always hot?
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The temperature inside the Earth increases with depth, about 1°C for every 32 meters. In the mantle region, temperatures can reach around 2200°C. At such high temperatures, rocks melt and exist in a hot, molten state called magma. During volcanic eruptions, this extremely hot magma rises and escapes to the surface, which is why the material that comes out is always hot.
2
'Without earth's magnetic property the solar wind would erode our atmosphere and we could be de-void of our life sustaining gases'. (space.com)
Which layer of earth is working as the magnetic field and why?
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The Earth's magnetic field is generated by its core, which is composed mainly of iron and nickel. The movement of molten iron in the outer core creates electric currents, which in turn produce the magnetic field. This magnetic field acts as a shield, protecting our atmosphere from harmful solar winds
1
Assertion (A): Sima is floating on Sial.
Reason (R): Sial is less dense than Sima.
- (a)Both A and R are true and R is the correct explanation of A.
- (b)Both A and R are true and R is not the correct explanation of. A.
- (c)A is true but R is false.
- (d)A is false but R is true.
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A is false but R is true.
Explanation — Sial floats on Sima, as Sial is less dense than Sima.
2
Assertion (A): The Gutenburg discontinuity is situated between Mantle and core.
Reason (R): There is a sudden change in the velocity of earthquake waves between mantle and core.
- (a)Both A and R are true and R is the correct explanation of A.
- (b)Both A and R are true and R is not the correct explanation of A.
- (c)A is true but R is false.
- (d)A is false but R is true.
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Both A and R are true and R is the correct explanation of A.
Explanation — The Gutenburg discontinuity is situated between the Mantle and the core. This is the area where some earthquake waves are absorbed or change speed, hence there is sudden change in the velocity of these waves.
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