Question

Which of the following free radicals helps in depletion of the ozone layer?

• A. NO
• B. Cl
• C. OH
• D. CH3

Answer 1

Answer: (B)

Cl

Answer 2

The correct option is (B): Cl

The depletion of the ozone layer is mainly caused by the presence of free radicals containing chlorine and/or bromine atoms, which are collectively referred to as halogen radicals.

The two most important halogen radicals responsible for the depletion of the ozone layer are:

1. Chlorine radical (Cl•)
2. Bromine radical (Br•)

These free radicals are formed from the breakdown of chlorofluorocarbons (CFCs) and other halogenated compounds, which were widely used as refrigerants, propellants, and solvents before their harmful effects on the ozone layer were discovered.

When CFCs and other halogenated compounds are released into the atmosphere, they are carried up into the stratosphere by natural air currents. In the stratosphere, the compounds are broken down by the intense ultraviolet radiation from the sun, releasing chlorine and/or bromine atoms as free radicals.

Once released, these halogen radicals can react with ozone (O3) molecules, breaking them down into oxygen (O2) molecules and leaving behind more free radicals to continue the cycle of ozone destruction. This process is known as ozone depletion and leads to the thinning of the ozone layer.

Therefore, the free radicals that help in the depletion of the ozone layer are the halogen radicals, particularly the chlorine and bromine radicals.