Question

The core is made of two layers: the outer core, which borders the mantle, and the inner core. The inner core is shaped like a ball. Iron and nickel in the outer core form an alloy, or a mixture of metallic elements. The outer core is approximately 2,300 kilometers thick and very hot, between 4,000 and 5,000 degrees Celsius. The inner core is made mostly of iron. It is about 1,200 kilometers thick and extremely hot, between 5,000 and 7,000 degrees Celsius.

Why is the inner core solid?

A It is solid because it is magnetic.
B It is solid because it is composed of heavy metals.
C It is solid because it exists at such high temperatures.
D It is solid because it is experiencing very high pressure.

Answer 1

D

The inner core is solid because the enormous pressure at Earth's center raises the melting point of iron and other metals so high that, despite the very high temperature, the material remains solid.