Consider the following statements:

1. Statement-I: Rainfall is one of the reasons for weathering of rocks.
2. Statement-II: Rain water contains carbon dioxide in solution.
3. Statement-III : Rain water contains atmospheric oxygen.

Which one of the following is correct in respect of the above statements?

1. Both Statement-II and Statement-III are correct and both of them explain Statement-I
2. Both Statement-II and Statement-III are correct, but only one of them explains Statement-I
3. Only one of the Statements II and III is correct and that explains Statement-I
4. Neither Statement-II nor Statement-III is correct

Explanation

Both Statement-II and Statement-III are correct and both of them explain Statement-I

• Rainfall plays a significant role in the weathering of rocks through physical, chemical, and biological processes. As rainwater falls, it absorbs carbon dioxide from the atmosphere, forming carbonic acid, which contributes to the chemical weathering of rocks. Rainwater also contains dissolved gases such as carbon dioxide, nitrogen, and sulphur oxides, which lower its pH to around 5.5 or less, enhancing its corrosive effects. Additionally, dissolved oxygen in rainwater supports oxidation reactions, further promoting chemical weathering of certain rock minerals.

Answer: (a) Both Statement-II and Statement-III are correct and both of them explain Statement-I; Difficulty Level: Easy