Question 47

Magma that has cooled and solidified on Earth's surface is best described as igneous rock.

When magma cools and solidifies on the Earth's surface, it forms igneous rock. This process typically occurs after volcanic eruptions, where the molten rock (magma) is exposed to cooler temperatures and begins to solidify.

A) Clay

Clay is a fine-grained natural soil material that becomes plastic when wet and hardens when fired. It is not formed from cooled magma but rather from the weathering of rocks and minerals, making it irrelevant in the context of solidified magma.

B) Iron ore

Iron ore refers to rocks and minerals from which metallic iron can be economically extracted. While iron ore can be found in igneous rocks, it is not a product of solidified magma itself and does not define the cooling and solidification process of magma on the Earth's surface.

C) Igneous rock

Igneous rock is formed directly from the cooling and solidification of magma or lava. This definition precisely matches the description given in the question, as it explicitly refers to the end product of magma that has cooled on the Earth's surface.

D) Volcanic ash

Volcanic ash consists of tiny fragments of rock and mineral matter that are ejected during volcanic eruptions. Though it may be associated with volcanic activity, it is not a solidified form of magma, but rather a byproduct of explosive eruptions, distinguishing it from the category of igneous rock.

Conclusion

Igneous rock is the correct answer as it directly describes the result of magma cooling and solidifying on the Earth's surface. Other options, such as clay, iron ore, and volcanic ash, do not accurately define this geological process and are therefore incorrect. Understanding the formation of igneous rock is crucial in geology, highlighting the importance of magma's transition to solid form.