Which of the following pollutants are responsible for depletion of ozone layer?

Stratospheric ozone depletion is driven specifically by pollutants that release reactive halogen atoms — chlorine or bromine — into the stratosphere. Each such atom acts as a catalyst, destroying thousands of ozone (O3) molecules through a repeating chain reaction before it is finally removed from the atmosphere.

Applying this to chlorofluorocarbons (CFCs):

1. CFCs are chemically stable and unreactive in the lower atmosphere, so they persist for decades and gradually drift upward into the stratosphere.

2. In the stratosphere, intense ultraviolet radiation breaks the carbon–chlorine bond in the CFC molecule, releasing a free chlorine atom.

3. The chlorine atom reacts with an ozone molecule: Cl + O3 → ClO + O2, converting ozone into ordinary oxygen and depleting the ozone layer.

4. The chlorine atom is then regenerated — ClO + O → Cl + O2 — freeing it to repeat this destructive cycle thousands of times. This catalytic chain is why even trace amounts of CFCs cause large-scale ozone loss.

Comparing the other pollutants by their actual atmospheric role:

• Carbon dioxide and carbon monoxide are combustion-related gases that act at ground level and in the lower atmosphere — carbon dioxide traps infrared radiation (the greenhouse effect) and carbon monoxide affects air quality; neither carries a halogen atom into the stratosphere.

• Acid rain is precipitation made abnormally acidic when sulfur dioxide and nitrogen oxides dissolve into atmospheric moisture; its impact is on soils, water bodies, and structures at the surface, not on stratospheric ozone chemistry.

• Methane and carbon dioxide are greenhouse gases that trap heat in the lower atmosphere; this heat-trapping role is chemically distinct from the halogen-driven catalytic destruction that depletes stratospheric ozone.

Because chlorofluorocarbons uniquely supply the chlorine atoms that drive this catalytic destruction cycle, they are the pollutants responsible for depletion of the ozone layer.