How do igneous rock form?
A. From the cementing of sediments
B. From the cooling of magma
C. From the modification of existing rock
D. From the evaporation of water
B. From the cooling of magma
The correct answer is B. Igneous rocks form from the cooling of magma.
To understand how igneous rocks form, we need to know that magma is molten rock that is found beneath the Earth's surface. When magma cools and solidifies, it forms igneous rocks. This cooling can happen either slowly beneath the Earth's surface or quickly during volcanic eruptions.
To choose the correct answer B, we need to review the given options:
A. From the cementing of sediments: This describes how sedimentary rocks form, not igneous rocks. Sedimentary rocks form when layers of sediment are compacted and cemented together over time.
B. From the cooling of magma: This option correctly describes the process of how igneous rocks form. As mentioned earlier, when magma cools and solidifies, it forms igneous rocks. This occurs through a process called crystallization, where the minerals in the magma rearrange themselves into a solid state.
C. From the modification of existing rock: This describes how metamorphic rocks form, not igneous rocks. Metamorphic rocks form when existing rocks are subjected to intense heat or pressure, causing them to undergo changes in composition and structure.
D. From the evaporation of water: This option describes how some sedimentary rocks, called evaporites, form as a result of the evaporation of water. Examples of evaporites include rock salt and gypsum.
Therefore, the correct answer is B, From the cooling of magma.