Artificial way of causing rainfall to reduce air pollution makes use of
- (a) silver iodide and potassium iodide ✓ UPSC's answer
- (b) silver nitrate and potassium iodide
- (c) silver iodide and potassium nitrate
- (d) silver nitrate and potassium chloride
Why the answer is (a)
• Cloud seeding induces rain by dispersing particles into clouds that act as nuclei on which water droplets or ice crystals form and grow until they fall.
• The classic seeding agents are silver iodide, whose crystal structure resembles ice and triggers freezing in supercooled clouds, and potassium iodide, often burnt together with it in flares; dry ice and common salt are also used.
• Delhi has explored cloud seeding with IIT Kanpur to wash pollutants out of the air during winter smog.
• Silver nitrate, potassium nitrate and potassium chloride are not seeding agents.
• Hence option (a).
Why the other options are wrong
- (b) silver nitrate and potassium iodide
- Silver nitrate is not a cloud-seeding agent; silver iodide is.
- (c) silver iodide and potassium nitrate
- Potassium nitrate is not used; potassium iodide is.
- (d) silver nitrate and potassium chloride
- Neither silver nitrate nor potassium chloride is a standard seeding agent.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2025, held on 25 May 2025. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.