Question

the shadow zone exists because?
a. seismic waves cannot travel through solid rock.
b. sunlight blocks out p waves in certain regions.
c. p waves refract as they travel through earth.
d. the mantle and core are composed of the same material.

Explanation:

• Option A: Seismic waves (both P - waves and S - waves) can travel through solid rock. S - waves cannot travel through liquids, but P - waves can travel through solids, liquids, and gases. So this option is incorrect.
• Option B: Sunlight has no relation to the shadow zone of seismic waves. The shadow zone is related to the behavior of seismic waves (P and S waves) as they travel through the Earth's interior. So this option is incorrect.
• Option C: The shadow zone for P - waves exists because P - waves refract as they travel through different layers of the Earth with different densities. When P - waves enter the liquid outer core, their speed changes (decreases), and they refract. This causes a region (shadow zone) where these refracted P - waves are not directly detected at certain distances from the earthquake epicenter.
• Option D: The mantle and core are composed of different materials. The mantle is solid (with some semi - molten regions in the asthenosphere), and the outer core is liquid. So this option is incorrect.

Answer:

C. P waves refract as they travel through Earth.