Ncert Exercises & Solutions

Which of the following statements is correct?

1.	Ozone hole is a hole formed in stratosphere from which ozone oozes out
2.	Ozone hole is a hole formed in troposphere from which ozone oozes out
3.	Ozone hole is thinning of ozone layer of stratosphere at some places
4.	Ozone hole means vanishing of ozone layer around the earth completely

Ozone hole is thinning of ozone layer of atmosphere at some place.

Two types of compounds have been found to be the most responsible for depleting ozone layer.

These are (i) NO (ii) chlorofluorocarbon

NO + O_{3} \to {NO}_{2} + O_{2}

{CF}_{2} {Cl}_{2} \overset{hv}{\to} * {CF}_{2} Cl + Cl *

Cl * + O_{3} \to ClO * + O_{2}

ClO * + O \to Cl * + O_{2}

These reactions occur in stratosphere.