AFOQT Practice Test

Which type of rock is formed from the cooling of molten rock?

1. Metamorphic rock

2. Sedimentary rock

3. Igneous rock

4. Organic rock

The correct answer is: Igneous rock

Igneous rock is formed from the cooling and solidification of molten rock, known as magma when it is beneath the Earth's surface and lava when it erupts onto the surface. As the molten material cools, it crystallizes into solid rock. This process can occur either from volcanic activity, where the lava cools quickly upon exposure to air or water, leading to fine-grained textures, or from slower cooling beneath the surface, which results in coarser-grained textures. In contrast, metamorphic rock is created from the alteration of existing rocks through heat, pressure, and chemical processes. Sedimentary rock forms from the accumulation and compaction of mineral and organic particles, while organic rock typically refers to sedimentary rock that consists of the remains of living organisms. Each of these rock types has a different formation process, with igneous rock specifically linked to the cooling of molten rock. Therefore, the correct answer is igneous rock.