Question

3 of 5 next 03:05 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.

Explanation:

To determine why the inner core is solid, we analyze each option:

• Option A: Magnetism doesn't determine the state (solid/liquid) of a substance. The inner core's magnetism is a result of other factors, not the reason for it being solid. Eliminate A.
• Option B: Being composed of heavy metals (iron) alone doesn't make it solid. The outer core also has iron and nickel (heavy metals) but is liquid. Eliminate B.
• Option C: High temperatures generally favor a liquid or gaseous state (as seen in the outer core which is hot and liquid). So high temperature alone can't explain why the inner core is solid. Eliminate C.
• Option D: The inner core is under extremely high pressure from the overlying layers of the Earth. High pressure can force materials into a solid state even at high temperatures. This matches the scientific understanding of the inner core's state.

Answer:

D. It is solid because it is experiencing very high pressure.