Answer: Provide surfaces that convert inactive chlorine reservoirs to Cl2.
- A Directly absorb and destroy ozone molecules
- B Warm the stratosphere and speed up all the chemical reactions
- C Provide surfaces that convert inactive chlorine reservoirs to Cl2
- D Emit chlorofluorocarbons stored during winter
Correct answer: C. Provide surfaces that convert inactive chlorine reservoirs to Cl2
Explanation: On ice-cloud surfaces, reservoir species (ClONO2, HCl) are converted to Cl2 during the polar winter; returning spring sunlight photolyses Cl2 to Cl radicals that catalytically destroy ozone.
Classical smog is a reducing mixture of SO₂ and fog, while photochemical smog is an oxidising mixture generated by UV-driven reactions of NOx and hydrocarbons.
Concept context
Understand how human activities alter the atmosphere, water, and soil. Covers air pollutants, smog types, ozone depletion, acid rain, greenhouse effect, water and soil pollution, and the principles of green chemistry.