Which of following is harmful to the ozone layer by decomposing O3 to O2?

carbon dioxide

sulfur dioxide

greenhouse gases

chlorofluorocarbons

We have to get the compound which is harmful to ozone layer by decomposing O₃ to O₂.

Chlorofluorocarbon (CFC) is responsible for ozone layer decomposition.

When chlorofluorocarbon (CFC) is released in atmosphere, they mix with normal atmospheric gas and reaches to stratosphere. In stratosphere, they get broken down by powerful UV radiations, releasing chlorine free radical.

CF₂Cl₂ (g) → Cl· (g) + CF₂Cl· (g)

The chlorine radical then reacts with stratospheric ozone to form chlorine monoxide radical and molecular oxygen.

Cl· (g) + O₃ (g) → ClO· (g) + O₂ (g)

Reaction of chlorine monoxide radical with atomic oxygen produces more chlorine radicals.

ClO· (g) + O (g) → Cl· (g) + O₂ (g)

The chlorine radicals are continuously produced and cause depletion of ozone. This damages ozone layer.