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UPSC Prelims 2025 GS Paper 1, question 85

Topic: Environment and ecology

Q85

Artificial way of causing rainfall to reduce air pollution makes use of

  1. (a) silver iodide and potassium iodideCorrect answer
  2. (b) silver nitrate and potassium iodide
  3. (c) silver iodide and potassium nitrate
  4. (d) silver nitrate and potassium chloride

Solution.

Answer: (a) silver iodide and potassium iodide

  1. Artificial rainmaking (cloud seeding) disperses glaciogenic or hygroscopic nuclei into supercooled clouds to induce ice-crystal formation or droplet coalescence.
  2. Silver iodide (whose hexagonal crystal lattice closely mimics natural ice) and potassium iodide (along with dry ice and common salt) are the standard chemical agents used in cloud seeding.