On the basis of chemical reactions involved, explain how do chlorofluorocarbons cause thinning of ozone layer in stratosphere.

In the stratosphere due to the action of U.V rays causes the dissociation of cloroflorocarbons to realese the free chlorine radicle as shown in the equation below:

CF₂Cl₂ + U V radiations → Cl + CFCl

Now this Chlorine radicle so formed is free and in the stratospheric layer reacts with the Ozone to form Chlorine monoxide and oxygen as shown in the equation below:

Cl (g) +O₃ (g) → ClO (g)+O₂(g)

Now further the reaction of chlorine monoxide with the nascent oxygen ie. Oxygen atom leads to the formation of oxygen and again chlorine free radical is formed as shown in the equation below:

ClO (g) + O (g) →Cl + O₂

This way Chlorine radicles are being regenerated and are reacting with ozone layer. So, CFCs are considered as the source of chlorine radicles which are destroying the ozone layer of stratosphere.