Answer: Cl is regenerated unchanged at the end of each catalytic cycle, repeating the process thousands of times.
- A Each CFC molecule releases 105 Cl radicals when it absorbs UV
- B Cl reacts with multiple O3 molecules simultaneously in a single collision
- C Cl is regenerated unchanged at the end of each catalytic cycle, repeating the process thousands of times
- D The reaction requires only visible light and produces Cl2, which attacks further O3 more efficiently
Correct answer: C. Cl is regenerated unchanged at the end of each catalytic cycle, repeating the process thousands of times
Explanation: The cycle is: Cl + O3 → ClO + O2 (step 1); ClO + O → Cl + O2 (step 2). Cl is consumed in step 1 but regenerated in step 2 - it acts as a catalyst. A single Cl atom repeats this cycle approximately 105 times before being removed by other atmospheric reactions, making the damage enormous.
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.