Consider the following statements :

Statement-I: Rainfall is one of the reasons for weathering of rocks.

Statement-II : Rain water contains carbon dioxide in solution.

Statement-III: Rain water contains atmospheric oxygen.

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

The correct option is: Both Statement-II and Statement-III are correct and both of them explain Statement-I.

Analysis of Statement-I:
Statement-I asserts that rainfall is one of the reasons for the weathering of rocks. Weathering is the breakdown or dissolution of rocks and minerals on the Earth's surface. Rainfall contributes to weathering through both mechanical processes (such as physical impact and expansion/contraction) and chemical processes (where water acts as a medium or reactant). Therefore, Statement-I is correct.

Analysis of Statement-II:
Statement-II states that rain water contains carbon dioxide in solution. As rain falls through the atmosphere, it naturally dissolves carbon dioxide (CO₂) from the air, forming a weak carbonic acid (H₂CO₃). This acidic rainwater reacts chemically with minerals in rocks (particularly carbonate rocks like limestone), leading to chemical weathering (carbonation). Thus, Statement-II is correct, and it directly explains how rainfall causes the weathering of rocks (explaining Statement-I).

Analysis of Statement-III:
Statement-III states that rain water contains atmospheric oxygen. Falling rain also dissolves atmospheric oxygen (O₂). When this oxygen-rich water comes into contact with rocks containing iron-bearing minerals, a chemical reaction called oxidation occurs (commonly known as rusting). This breaks down the mineral structure, leading to rock weathering. Thus, Statement-III is correct, and it also directly explains how rainfall causes the weathering of rocks (explaining Statement-I).

Conclusion:
Since both dissolved carbon dioxide (forming carbonic acid) and dissolved oxygen in rainwater drive major chemical weathering processes (carbonation and oxidation respectively), both Statement-II and Statement-III are correct and both serve as scientific explanations for the weathering described in Statement-I.