Repeated freezing and thawing of water in rock cracks is known as what?

Correct answer: Frost weathering

The direct answer is C, Frost weathering. Weathering means breaking or changing rock at or near Earth’s surface without transporting it away. In cold places, water enters a crack, freezes, expands, and pushes the crack walls apart. When it melts, more water can enter. Repeated freezing and thawing gradually widens the crack and breaks the rock into pieces, so this is physical or mechanical weathering. Option A, carbonation, is a chemical reaction in which carbonic acid in water reacts with minerals, especially limestone. Option B, oxidation, is a chemical change often involving oxygen, such as rusting of iron-bearing minerals. Option C is correct because it names the repeated freezing-and-thawing process. Option D, hydration, means minerals take in water and change chemically or expand; it is not the specific process described here. Memory cue: frost means freezing, so frost weathering means ice breaking rock.