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🧪 Chemistry  ·  Environmental Chemistry  ·  NEET & JEE

A single chlorine radical from a CFC can destroy ozone catalytically, meaning it can break down:

Answer: many O₃ molecules.

  • A just one O₃ molecule
  • B many O₃ molecules
  • C no O₃ molecules
  • D only O₂ molecules

Correct answer: B. many O₃ molecules

Explanation: Because the Cl atom is regenerated in each cycle, one radical can destroy thousands of ozone molecules.

Classical (London) SmogSources: coal burningSO₂ + particulates + fogReducing typeConditions: cold, humid,early morning, winterVisibility: very low (fog)London, 1952 - ~4000 deathsHarms: eyes, lungs, bronchitisPhotochemical (LA) SmogSources: vehicles, industriesNOx + hydrocarbons + UVOxidising typeConditions: warm, sunny,afternoon, summerProducts: O₃, PAN, acroleinLos Angeles (common in cities)Harms: eyes, rubber cracking

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.

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