Scientists use the properties of seismic waves to figure out the structure of Earth's interior. For example, seismic waves travel faster through denser layers than through less dense layers. Also, P waves can travel through both solids and liquids, but S waves can travel through solids only.

Question

Because P and S waves travel faster through the Earth's mantle than through Earth's crust, scientists know that the mantle is _______ and _______ than the crust.
solid; less dense
liquid; less dense
solid; denser
liquid; denser

Answer 1

The correct answer is: solid; denser.

This is because seismic waves, particularly P waves, travel faster through the mantle, indicating that it is a solid material, and the fact that they travel faster in the mantle than in the crust suggests that the mantle is denser than the crust.