The Core

What is the approximate radius of Earth's inner core?

• 300 miles (480 km)

• 760 miles (1,220 km)

• 1,500 miles (2,400 km)

• 3,700 miles (6,000 km)

What element is estimated to make up over 80% of Earth's core?

• Oxygen

• Silicon

• Iron

• Nickel

How did scientists determine that Earth's outer core is liquid?

• By observing the effects of gravity on the Earth's surface.

• By conducting experiments on iron and silicate under extreme pressure.

• By studying seismic S-waves, which cannot pass through liquid material.

• By analyzing the density differences between the Earth's surface and its core.

What is the approximate temperature of Earth's inner core and its melting point?

• 9,800°F and 11,000°F

• 2,800°F and 9,800°F

• 11,000°F and 2,800°F

• 5,230°F and 6,000°F

What contributes to the Earth's core remaining hot?

• Heat generated by the friction of dense materials.

• The continuous cooling of the Earth's crust.

• Absorption of solar energy by the inner layers.

• Chemical reactions between the core and the mantle.