Question

Choose the answer that best explains how extrusive igneous rocks are different from intrusive igneous rocks.

a) Extrusive rocks cool faster, resulting in larger crystals.
b) Intrusive rocks form on the Earth's surface.
c) Extrusive rocks have finer grains due to rapid cooling on the surface.
d) Intrusive rocks have a glassy texture compared to extrusive rocks.

Answer 1

Extrusive igneous rocks differ from intrusive ones by cooling quickly on the Earth's surface, which leads to finer grains, while intrusive rocks cool slowly underground, forming coarse-grained crystals.

Step-by-step explanation:

Extrusive igneous rocks are different from intrusive igneous rocks primarily in the rate at which they cool and solidify, which affects their texture.

Extrusive rocks form when magma reaches the Earth's surface and cools quickly, resulting in a fine-grained or glassy texture with very small or no visible crystals.

Intrusive rocks, on the other hand, form within the Earth's crust where the magma cools slowly, allowing for the growth of larger, coarse-grained crystal structures. So, the correct answer to the question is c) Extrusive rocks have finer grains due to rapid cooling on the surface.