Which of the following gases is primarily responsible for the depletion of the ozone layer in the stratosphere?

Solution

1. The ozone layer is depleted by reactive species in the stratosphere.
2. Chlorofluorocarbons ($\text{CFCs}$) release chlorine atoms upon exposure to ultraviolet radiation.
3. These chlorine atoms react with ozone (${\text{O}}_3$) to form oxygen (${\text{O}}_2$).
4. Hence the answer is (A).