Which statement correctly describes the Earth's outer core?

Which statement correctly describes the Earth's outer core?

• A. It is a liquid layer composed mainly of iron and nickel.
• B. It is a solid iron ball.
• C. It is a gas.
• D. It is a crust.

Answer: (A)

The outer core is a liquid layer of iron and nickel surrounding the inner core. Its molten state arises from extremely high temperatures that keep iron liquid even under immense pressures. This moving liquid iron generates Earth's magnetic field through a geodynamo process, a flow-driven electrical current in the conducting metal. Seismic evidence supports a liquid state because shear waves cannot pass through liquids, and compressional waves slow and change speed as they travel through this layer. The other descriptions don’t fit: it isn’t a solid iron ball (that would be the inner core), it isn’t a gas, and it isn’t the crust.

The outer core is a liquid layer of iron and nickel surrounding the inner core. Its molten state arises from extremely high temperatures that keep iron liquid even under immense pressures. This moving liquid iron generates Earth's magnetic field through a geodynamo process, a flow-driven electrical current in the conducting metal. Seismic evidence supports a liquid state because shear waves cannot pass through liquids, and compressional waves slow and change speed as they travel through this layer. The other descriptions don’t fit: it isn’t a solid iron ball (that would be the inner core), it isn’t a gas, and it isn’t the crust.