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. solid; less dense
b. liquid; denser
c. liquid; less dense
d. solid; denser

Explanation:

1. Recall the properties of Earth's mantle and crust: The mantle is a solid layer (S - waves can travel through it, and S - waves only travel through solids).
2. Recall the relationship between seismic wave speed and density: Seismic waves travel faster through denser materials. Since P and S waves travel faster through the mantle than the crust, the mantle must be denser than the crust.
3. Evaluate the options:

• Option A: Says mantle is solid (correct) but less dense (incorrect, as waves travel faster through denser materials).
• Option B: Says mantle is liquid (incorrect, S - waves travel through mantle, so it must be solid).
• Option C: Says mantle is liquid (incorrect) and less dense (incorrect).
• Option D: Says mantle is solid (correct, as S - waves can travel through it) and denser (correct, as seismic waves travel faster through denser layers, and they travel faster through mantle than crust).

Answer:

D. solid; denser