• # question_answer 52)   Ozone is a gas heavier than air. Why does ozone layer not settle down near the earth?

In stratosphere, the formation of ${{O}_{3}}$ goes on continuously, but ${{O}_{3}}$ is also decomposed by UV-radiation between 240 to360 nm. ${{O}_{3}}+hv\xrightarrow{(240-360nm)}{{O}_{2}}+O$ The O-atom reacts with second ${{O}_{3}}$ molecule. ${{O}_{3}}+O\to 2{{O}_{2}}$ Net reaction $2{{O}_{3}}\to 3{{O}_{2}}$ Thus, the reactions form a delicate balance in which the rate of ${{O}_{3}}$ decomposition matches the rate of ${{O}_{3}}$ formation, i.e., a dynamic equilibrium exists and maintains a constant concentration of${{O}_{3}}$.