Which statement correctly summarizes the effect of chemical weathering?

• A. Physical weathering disintegrates rocks without chemical changes.
• B. Chemical weathering causes rocks to disintegrate through chemical changes.
• C. Erosion removes rocks from the surface.
• D. Ice forms within rocks to break them apart.

Answer: (B)

Chemical weathering is a process where chemical reactions change minerals in rocks, altering their composition and structure so the rock can break down or dissolve. This is why the statement that chemical weathering causes rocks to disintegrate through chemical changes is best: the rock is actually altered at the mineral level, not just physically torn apart. Examples include feldspar turning into clay through hydrolysis, calcite dissolving in rainwater containing carbonic acid, and ferrous minerals oxidizing to form rust—all of which weaken the rock from the inside.

In contrast, physical (mechanical) weathering breaks rocks into smaller pieces without changing their mineral makeup, which is why descriptions of disintegration without chemical change don’t apply to chemical weathering. Erosion, meanwhile, describes the transportation of weathered material after it has formed, not the weathering process itself. Frost wedging, where ice expands in cracks to push rocks apart, is another physical weathering process.