Question

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.

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.
A.
liquid; denser
B.
solid; denser
C.
liquid; less dense
D.
solid; less dense

Answer 1

B. solid; denser

Explanation: S waves only travel through solids, so the mantle must be solid. Because seismic waves travel faster through denser material, the faster travel through the mantle means it is denser than the crust.