Question

 Depletion of ozone is mainly due to:
A. Chlorofluorocarbon compounds
B. Carbon monoxide
C. Methane
D. Pesticide

Answer 1

 Hint:Compounds containing elements known as halogen are considered to be mainly responsible for the ozone layer depletion. This is because, these elements i.e. halogens are highly electronegative and are non-metallic in nature. So, find out which compound in the options given has a halogen element.

Complete step by step answer:  
The Ozone layer is a shield of the earth’s stratosphere. In this layer, high concentration of ozone is situated compared to other parts of the atmosphere. Ozone absorbs almost all the harmful ultraviolet rays of the sun and protects us. Nowadays, ozone holes are being found which are referred to as the damage of the ozone layer.
The thinning of the ozone layer due to depletion in the concentration of ozone molecules is known as ozone depletion. Actually, the ozone layer damage is basically like a patch than a hole. This damage of the ozone layer is commonly known as ozone layer depletion. This ozone layer depletion is basically due to the ozone-depleting substances (ODS) which is emitted into the atmosphere. These substances consist of halocarbon refrigerants, solvents. Propellants, and foam blowing agents. But the major substances responsible for ozone depletion include chlorofluorocarbons or CFCs. These are compounds containing chlorine and fluorine. It is considered as a main reason for $80%$ ozone layer depletion and basically comes from the refrigerator, air-conditioner, deodorant, etc.
Thus, from the given options we see that the first option is a halocarbon compound i.e. chlorofluorocarbon which contributes to $80%$ if the ozone layer depletion.
Hence, the correct option is A.

Note: When chlorine atoms of chlorofluorocarbon come into contact with ozone in the stratosphere, it destroys ${{O}_{3}}$ molecules by converting ${{O}_{3}}$ molecules into ${{O}_{2}}+O$. One $Cl$ atom can destroy almost $100,000$ ozone molecules. So, ozone is destroying more quickly than it is naturally creating. So, a hole is formed in the ozone layer, called an ozone hole.