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Physical and World Geography MCQs – 02 (Interior of the Earth)

 Interior of Earth MCQs with answers and explanations for all examinations.

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1. Consider the following statements:

1. The uppermost layer over the earth surface is called the “crust” and it is the thinnest of all the layers.
2. The thickness of the ocean crust is more than the continental crust.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (a) 1 only 

  • Layers of earthThe interior of the earth can be divided into 3 different layers:
    • Crust
    • Mantle 
    • Core
  • The uppermost layer over the earth’s surface is called the crust. It is the thinnest of all the layers. 
  • It is fragile and brittle.
  • It is about 35 kms on the continental masses and only 5 km on the ocean floors. 
  • Hence, The thickness of the continental crust is more than the ocean crust.

2. Consider the following statements:

1. The Mantle has a density higher than the Crust.
2. The asthenosphere is the lower portion of Mantle.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (a) 1 only 

  • The portion of the interior below the crust is called the mantle.
  • The Mantle has a density higher than the crust.
  • The mantle extends up to a depth of 2,900 km.
  • The asthenosphere, which is the chief source of magma, forms the upper portion of Mantle.
  • The crust and the uppermost part of the mantle are called the Lithosphere.
  • The major constituents of the mantle are Silicon and Magnesium and hence it is often termed as SIMA.

3. Consider the following statements:

1. The core is made up of very light materials like Silica (Si) and Aluminium (Al).
2. The inner core is in the solid-state whereas the outer core is in the liquid state.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (b) 2 only 

  • The portion of the interior beyond the mantle is known as Core.
  • The Core consists of two sub-layers:
    • The inner core
    • The outer core
  • The inner core is in the solid-state whereas the outer core is in the liquid state. 
  • The inner core stays solid because of the large pressure surrounding it.
  • Core is made up of very heavy materials like Nickel and Iron. Hence it is often called the “NIFE” layer.
  • The core is the densest layer of the earth with its density ranging between 9.5 -14.5 g/cm3.
  • It is to be noted that Silica (Si) and Aluminum (Al) are major constituents of the crust due to which it is often termed as SIAL.

4. Consider the following statements:

1. Transition zone between Mantle and Core is known as Gutenberg Discontinuity.
2. Transition zone between the Crust and Mantle is known as Mohorovicic Discontinuity.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2 

  • Transition zone between the Crust and Mantle is known as Mohorovicic Discontinuity.
  • Transition zone between Mantle and Core is known as Gutenberg Discontinuity.

5. Consider the following statements:

1. Continental crust is mainly made from a rock called granite.
2. Oceanic crust is mainly made from a rock called basalt.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2 

  • Continental crust is mainly made up of granite, sedimentary rocks and metamorphic rocks.
  • Oceanic crust is mainly made from a rock called basalt.

6. Consider the following statements:

1. The transition zone between the upper core and the lower core is called Lehmann Discontinuity.
2. The transition zone between the upper mantle and the lower mantle is known as Repetti Discontinuity.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2 

  • The transition zone between the upper core and the lower core is called Lehmann Discontinuity.
  • The transition zone between the upper mantle and the lower mantle is known as Repetti Discontinuity.

7. Which among the following is not a source of Information about the interior of the earth ?

(a) Volcanic eruptions
(b) Meteors
(c) Seismic Waves
(d) Rivers

Correct Answer – (d) Rivers

  • Following are the main sources which provide Information about the interior of the earth: 
    • Volcanic eruptions
    • Rocks excavated in mining
    • Meteors
    • Seismic Waves
    • Gravity anomaly ( Change in gravity value according to the mass of material )

8. Consider the following statements:

1. Pressure increases from the surface towards the center of the earth.
2. Temperature decreases from the surface towards the center of the earth.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (a) 1 only 

  • Pressure increases from the surface towards the center of the earth due to the large weight of the overlying materials and rocks.
  • Temperature decreases from the surface towards the center of the earth as evident from the molten lava erupted from the earth’s interior.
  • It is to be noted that the density also increases from the surface towards the center of the earth.

9. Consider the following statements:

1. Rocks formed when molten lava comes on the earth’s surface, cools down and becomes solid are called extrusive Igneous rocks.
2. Rocks formed when molten lava cools down deep inside the earth’s crust and becomes solid are called intrusive Igneous rocks.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2 

  • Rocks formed when molten lava comes on the earth’s surface, cools down and becomes solid are called extrusive Igneous rocks.
  • Rocks formed when molten lava cools down deep inside the earth’s crust and becomes solid are called intrusive Igneous rocks.

10. Consider the following statements:

1. Extrusive igneous rocks are made up of large grains.
2. Intrusive igneous rocks have a very fine grained structure.

Which of the above statements is/are true?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (c) Both 1 and 2 

  • Extrusive igneous rocks have a very fine grained structure due to sudden cooling. 
  • Example – Basalt.
  • Intrusive igneous rocks are made up of large grains.
  • Example – Granite.

11. Consider the following statements about sedimentary rocks ?

1. These are formed by the deposition of various types of sediments in layers.
2. There is no possibility of finding fossils in these rocks.

Select the correct statements from the codes below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer – (a) 1 only

  • The earth’s crust is composed of different types of rocks. 
  • There are mainly three types of rocks:
  • Igneous Rocks:
    • Formed by the solidification of magma and lava. 
    • Example – Granite, Gabbro and Basalt etc.
  • Sedimentary Rocks: 
    • Formed as a result of deposition of fragments of rocks by wind, water, etc.
    • Example – Sandstone, Limestone, Shale etc.
    • These rocks may also contain fossils of plants, animals and other microorganisms that once lived on them.
  • Metamorphic Rocks: 
    • Formed from already-existing rocks that undergo recrystallization due to high temperature or pressure or both. 
    • Example –  Schist, Gneiss, Quartzite and Marble etc.

12. Consider the following statements about Igneous Rocks ?

1. Igneous rocks are primary rocks.
2. Igneous rocks can be changed into sedimentary rocks but not into metamorphic rocks.

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2 

Correct Answer – (a) 1 only

  • Igneous rocks are primary rocks.
  • Sedimentary and metamorphic rocks are formed from these primary rocks.
  • Igneous rocks can be changed into metamorphic rocks. They can also be converted into Sedimentary rocks by the process of lithification.

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