Which of the following is NOT an example of chemical weathering?

a. natural plant acid breaking down a rock

c. oxidation of metals

b. acid rain deteriorating a marble statue

d. ice wedging in rock

The correct answer to this question is D. Whilst the other options: natural plant acid breaking down rock, oxidation of metals and acid rain all refer to chemical weather, ice wedging in a rock would be referred to as mechanical weathering. This is due to the fact that the ice will only change the physical structure of the rock, rather than affecting it chemically.