(a) What is ozone? How is it formed in the upper layers of the Earth's atmosphere? How does ozone affect our ecosystem?

Ozone is a molecule formed by three atoms of oxygen.

UV radiations split some molecular oxygen \(\displaystyle \left(\mathrm{O}_{2}\right)\) into free oxygen atoms \(\displaystyle (\mathrm{O}+\mathrm{O})\). These atoms then combine with molecular oxygen to form ozone. / \[\begin{aligned} & \mathrm{O}_{2} \xrightarrow{\mathrm{UV}} \mathrm{O}+\mathrm{O} \\ & \mathrm{O}+\mathrm{O}_{2} \rightarrow \mathrm{O}_{3}(\mathrm{Ozone}) \end{aligned} \]

Ozone layer shields the surface of the earth from damaging UV radiation of the sun. / Depletion of ozone layer causes harmful effects on the organism.