Question

Crust describes the outermost shell of a terrestrial planet. Earth’s crust is relatively thin, just 40-kilometers (25-miles) deep. Earth's crust can be divided into two types: continental and oceanic. Which of these does NOT explain how these two types of crust differ?
A Continental crust is thicker than oceanic crust.
B Continental crust is less dense than oceanic crust.
C Continental crust granitic composition: oceanic crust basalt and gabbro.
D Continental crust enriched with Fe and Mg: oceanic enriched with Al and Si.
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

1) Which does NOT explain how continental and oceanic crust differ?
Answer: D
Reason: It's backwards — continental crust is enriched in aluminum and silicon (felsic), while oceanic crust is richer in iron and magnesium (mafic).

2) Why is the inner core solid?
Answer: D
Reason: The inner core remains solid despite very high temperatures because extreme pressure raises the melting point of iron–nickel alloy so it is solid there.