Which form of weathering is characterized by the alteration of the chemical composition of rocks?

Chemical weathering is the process that alters the chemical composition of rocks and minerals. It occurs when minerals react with water, air, or other chemicals, leading to the formation of new minerals and solubles that can be washed away. This form of weathering may involve reactions such as hydrolysis, oxidation, and carbonation, which fundamentally change the intrinsic properties of the rock material.

In contrast, physical and mechanical weathering focus on breaking rocks into smaller pieces without changing their chemical structure, often through processes like freezing and thawing, or the action of wind and water, which do not alter the mineral composition. Hydraulic weathering, while a term sometimes used, typically refers to the physical action of water rather than a specific weathering process and is not widely recognized as a distinct form of weathering in scientific contexts. Thus, the essence of chemical weathering lies in the transformation of the rock's makeup through chemical interactions, making it the correct choice for this question.