Question

Which of the following causes depletion of the ozone layer in the atmosphere?

• A. Carbon dioxide
• B. Argon
• C. Chlorofluorocarbon
• D. Nitrogen

Answer 1

The correct option is C

Chlorofluorocarbon

Ozone layer:

• It is a layer in the lower stratosphere in the atmosphere of the earth.
• When oxygen molecules in the air react with UV rays coming from the sun it gets converted into ozone.
• $\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{UV}\mathrm{rays}}{\to }\underset{\mathrm{Ozone}}{{\mathrm{O}}_3\left(\mathrm{g}\right)}$

Explanation of correct option. (C):

• Chlorofluorocarbon(CFC) commonly known as Freon is used in refrigerators, propellants, etc.
• When chlorofluorocarbons (CFC) drift upwards towards the stratosphere, they come in contact with the Ozone layer.
• This leads to a chemical reaction where the CFC molecules are broken up by ultraviolet radiation, releasing chlorine atoms, which are able to destroy ozone molecules.
• It causes depletion of the ozone layer because it reacts with ozone to convert it into oxygen gas.

Explanation of incorrect options:

• (A) Carbon dioxide is present in the air in a very minute amount(0.03%).
• (B) Argon is an inert gas present in the air, it makes up 0.94% of the atmosphere.
• (D) Nitrogen is a gas present in abundance in the air, the air consists of 78% nitrogen.

Hence, option (C) Chlorofluorocarbon is the correct answer.