Question

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

Which of the above statements is/are correct?

• A.
  1 only
• B.
  1 and 3 only
• C.
  2 and 3 only
• D.
  1, 2 and 3

Answer 1

The correct option is D

1, 2 and 3
Explanation:

Statement 1 is correct: There are three main sources of heat in the deep earth, namely:

• The heat formed when the planet formed and accreted, which has not yet been lost;
• Frictional heating, caused by denser core material sinking to the centre of the planet;
• The heat from the decay of radioactive elements.

Statement 2 is correct: The outer layer is the earth crust–the lithosphere consists of 2 parts – the upper part consists of granitic rocks and forms the continents which comprise silica and alumina which have a density of 2.7.

Statement 3 is correct: The lower part consists of basaltic rocks and forms the oceans which comprise silica, iron and magnesium which has an average density of 3.0.