Question

Q. Consider the following statements with respect to the interior structure of the earth:

Which of the statements given above is/are correct?

• A. 1 only
• B. 2 only
• C. Both 1 and 2
• D. Neither 1 nor 2

Answer 1

The correct option is C Both 1 and 2

Explanation:

Statement 1 is correct: The crust is the outermost solid part of the earth.

• It is fragile in nature.
• It’s a solid rock layer divided into two types:
  • Continental crust encompasses the land and,
  • Oceanic crust encompasses water
• The thickness of the crust varies under the oceanic and continental areas.
• Oceanic crust is thinner as compared to continental crust.
• The kind of rock seen in the oceanic crust is basaltic and in the continental crust is granitic.
• The mean density of material in the oceanic crust is 3 g/cm3 and of continental crust is 2.7g/cm3.

Statement 2 is correct:

Mantle:

• The layer below the solid crust is the mantle.
• It forms about 84 percent of the earth’s volume and holds 68% of the earth’s mass.
• It is in solid-state and its density is higher than the crust.
• The major constituent elements of the mantle are Silicon and Magnesium and hence, it is also termed as SIMA.
• The upper portion of the mantle is called the asthenosphere. The word astheno means weak.
• It is considered to be extending up to 400 km. It is the main source of magma that finds its way to the surface during volcanic eruptions.