Which of the following statements best describes chemical weathering?
a. it happens only in cool environments.
b. it's the type of weathering in which rocks and minerals break down into smaller pieces.
c. it always results in dome-shaped formations.
d. it's the process by which rocks and minerals undergo changes in their composition.

A. It happens only in cool environments. 
B. It's the type of weathering in which rocks and minerals break down into smaller pieces. 
C. It always results in dome-shaped formations. 
D. It's the process by which rocks and minerals undergo changes in their composition

The statement that best describes chemical weathering is it is the process by which rocks and minerals undergo changes in their composition. The answer is letter D.