Which of the following is an example of chemical weathering?

The correct answer is the process of acid rain, which exemplifies chemical weathering. This occurs when rainwater, which has absorbed carbon dioxide from the atmosphere and other organic materials, becomes acidic and reacts with minerals in rocks. As a result, this chemical reaction alters the composition of the rock, leading to the breakdown of minerals and eventually the disintegration of the rock itself.

This process is distinct from physical weathering methods that physically break rocks apart without changing their chemical composition. For instance, frost wedging involves water seeping into cracks in rocks, freezing, and expanding, which physically breaks the rock apart but does not involve a chemical change. Similarly, heat expansion refers to the physical expansion of materials when exposed to heat, and salt wedging involves the crystallization of salt in rock crevices, which again is a physical process.

In summary, acid rain illustrates chemical weathering through its ability to chemically transform rock minerals, effectively demonstrating how environmental elements can lead to rock deterioration.