Which rock type is formed when molten material cools and solidifies?

• A. Igneous rock
• B. Sedimentary rock
• C. Metamorphic rock
• D. Organic rock

Answer: (A)

When molten material cools and solidifies, igneous rock forms. This molten material, magma when underground or lava when it erupts onto the surface, loses heat and crystallizes into minerals. The rate of cooling shapes the texture: slow cooling creates larger crystals like granite, while rapid cooling produces tiny crystals or a glassy texture like obsidian or basalt.

Sedimentary rocks come from deposited and pressed sediments or from mineral precipitation in layers, not from molten material cooling. Metamorphic rocks arise when existing rocks are altered by heat and pressure, changing minerals without melting. Organic rocks form from accumulated plant or animal matter, such as coal or limestone made from shells.