UPSC Prelims 2024 Question:

Consider the following statements

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

Statement -II: Rainwater contains carbon dioxide in solution. 

Statement-III: Rainwater contains atmospheric oxygen.

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

Explanation: 

• Rainfall and temperature can affect the rate at which rocks weather.
  
  
• High temperatures and greater rainfall increase the rate of chemical weathering
  
  
• Rocks in tropical regions are exposed to abundant rainfall and hot temperatures much faster than similar rocks residing in cold, dry regions.
  
  
• Rainwater - It is a form of natural water that can be categorized under the surface water as it is received as rainfall from the clouds.
  
• Gases that dissolve in rainwater before it reaches the ground:
  • Oxygen
  • Nitrogen
  • Carbon dioxide
    
    
• Rain is due to condensation of water droplets in the atmosphere. It does not contain any dissolved salts like ordinary water. Therefore rain water can dissolve more amount of oxygen than ordinary water. Moreover, rainwater is in contact with atmospheric air. Hence, it contains more percentage of oxygen. 
  

Therefore, option (1) is the correct answer.

Subject: Geography | Geomorphology