Question 1

What is considered the primary source of internal heat for the Earth?

Accepted Answer

Radioactive decay and primordial heat. The main sources of Earth's internal heat are the decay of radioactive isotopes and the residual heat from the planet's formation. This primordial heat has been trapped since the Earth coalesced. This heat drives geological processes like plate tectonics.

Question 2

Which layer of the Earth lies immediately beneath the crust?

Accepted Answer

Mantle. The Mantle lies immediately beneath the crust. It extends to a depth of approximately 2,900 kilometers. It is composed of silicate rocks that are richer in iron and magnesium than the crust.

Question 3

The 'Asthenosphere' is best described as which of the following?

Accepted Answer

A semi-fluid weak zone in the upper mantle. The Asthenosphere is a mechanically weak and ductile region of the upper mantle. It lies just below the lithosphere. Its semi-fluid nature allows tectonic plates to move over it.

Question 4

The core of the Earth is primarily composed of which two elements?

Accepted Answer

Nickel and Iron. The core is primarily composed of Nickel and Iron, often referred to as NIFE. It is the densest part of the Earth. Heavy metals sank to the center during the planetary differentiation process.

Question 5

Which components together constitute the 'Lithosphere'?

Accepted Answer

The Crust and the uppermost solid Mantle. The Lithosphere consists of the Crust and the uppermost rigid part of the Mantle. It behaves as a brittle, rigid solid. It is broken into tectonic plates that float on the asthenosphere.

Earth Structure — Set 1