Explain the relationship between CFCs and ozone in the stratosphere.

CFCs or Chlorofluorocarbons are strong ozone-depleting substances. They remain in the atmosphere for a long period of time. They enter the stratosphere from the troposphere, disintegrating slowly by the action of UV radiation and thus releasing Cl which causes ozone depletion as:-

In presence of UV radiations,

CFCl${}_3$ $\to$ CFCl${}_2$ + Cl

CF${}_2$Cl${}_2$ $\to$ CF${}_2$Cl+ Cl

This Cl reacts with O${}_3$ and converts it into O${}_2$

Cl +O${}_3$ $\to$ ClO + O${}_2$

ClO +O${}_3$ + O${}_2$

One chlorine atom can potentially destroy over 60,000 molecules of O${}_3$ in a year.

So, CFCs are gravely detrimental for the ozone layer.