Q. Which type of rock is formed from cooling and solidification of lava ?

Correct Answer: a) Igneous

Explanation: Igneous rocks are formed from the cooling and solidification of molten rock material, which can either be magma (inside the Earth’s crust) or lava (when it erupts onto the Earth’s surface). When lava cools and hardens, it forms igneous rocks. Examples of igneous rocks include basalt and granite.

Sedimentary rocks, on the other hand, are formed from the accumulation and compaction of sediments, while metamorphic rocks are formed when existing rocks are subjected to heat and pressure. Crystals are not a type of rock but rather a solid material with a specific atomic structure. Hence, the correct answer is igneous.