A dense sphere of solid iron and nickel at the center of the Earth is the ...

A dense sphere of solid iron and nickel at the center of the Earth is the ...

• A. Outer Core
• B. Inner Core
• C. Mantle
• D. Crust

Answer: (B)

The inner core is a solid sphere of iron and nickel at Earth's center. The immense pressures there keep iron in a solid state even at very high temperatures, so it forms a dense, solid ball. Surrounding it is the liquid iron–nickel outer core, which moves and convection in that liquid generates Earth's magnetic field. Outside the core lies the mantle, a thick layer of silicate rock, and the crust is the thin outer shell. Seismic evidence supports this layered picture: S-waves don’t travel through the liquid outer core, helping reveal the presence of a liquid layer around the solid center, while P-waves reveal transitions between the solid inner core, the liquid outer core, and the mantle.

The inner core is a solid sphere of iron and nickel at Earth's center. The immense pressures there keep iron in a solid state even at very high temperatures, so it forms a dense, solid ball. Surrounding it is the liquid iron–nickel outer core, which moves and convection in that liquid generates Earth's magnetic field. Outside the core lies the mantle, a thick layer of silicate rock, and the crust is the thin outer shell. Seismic evidence supports this layered picture: S-waves don’t travel through the liquid outer core, helping reveal the presence of a liquid layer around the solid center, while P-waves reveal transitions between the solid inner core, the liquid outer core, and the mantle.