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 answer is Option 1.Key Points

• Rainfall is one of the reasons for weathering of rocks. Hence, statement 1 is correct.
  • Weathering: The process of breaking down rocks into smaller pieces through physical, chemical, or biological means.
  • Rainfall's Role: Rainfall contributes to both physical weathering (by mechanical breakdown of rocks) and chemical weathering (by dissolving minerals in rocks).
• Rain water contains carbon dioxide in solution. Hence, statement 2 is correct.
  • Rain Water and CO₂: When rainwater falls through the atmosphere, it absorbs carbon dioxide (CO₂) from the air, forming a weak carbonic acid (H₂CO₃).
  • Chemical Weathering: This acidic rainwater can react with minerals in rocks, leading to chemical weathering.
• Rain water contains atmospheric oxygen. Hence, statement 3 is correct.
  • Oxygen in Rainwater: As rainwater falls through the atmosphere, it also dissolves atmospheric gases, including oxygen (O₂).
  • Presence of O₂: The dissolved oxygen can contribute to oxidation processes, which are part of chemical weathering.
• The presence of carbon dioxide in rainwater leads to the formation of weak carbonic acid, which causes chemical weathering, while the presence of atmospheric oxygen leads to oxidation reactions, another form of chemical weathering. Both processes contribute to the weathering of rocks. 
• Both Statement-II and Statement-III are correct, and both of them explain Statement-I.