Chlorofluorocarbons (CFCs) are important compounds that are used as refrigerants but these are also responsible for ozone layer depletion. If a chlorofluorocarbon CFCl3 is present in stratosphere, which of it's reaction intermediates are actually responsible for the breakdown of the ozone molecule?
Correct answer: B. Cl* and ClO*
- A. CFCl2* and Cl*
- B. Cl* and ClO*
- C. CFCl2* and ClO*
- D. CFCl2 and CFCl3
Explanation
Ozone breakdown is mediated by free radicals derived from CFCs. Free radicals have unpaired electrons and are highly unstable, thereby breaking down ozone into oxygen. As per the following reaction mechanism, you can see that chlorine radicals are the chief substance involved in ozone depletion, as it catalyses the breakdown of ozone into oxygen and gets regenerated at the end of the reaction via forming a ClO* intermediate, enabling it to break down more ozone molecules.As such, the option, containing Cl* and ClO*, is correct, which is option B.Option A contains a carbon or alkyl containing radical, which is not as reactive as chloride radical due to the presence of a stabilising carbon/ alkyl group, and does not mention ClO*. Option C does not mention the chloride radical.Option D merely mentions examples of CFCs.
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