How is ozone formed in the stratosphere? Why is it called good ozone? CFCs contribute to ozone-hole formation. Explain.

Formation of ozone in stratosphere :
(i) Nascent oxygen combines with molecular oxygen (O${}_2$ ) to form ozone by the action of UV-rays.
(ii) Ozone is degraded into molecular oxygen in the stratosphere by the action of UV rays to maintain its halo nee between production and degradation
Good ozone is formed in the stratosphere and absorbs harmful UV radiations from the sun. CFCs react with UV in stratosphere to release chloride atoms. Chloride atoms act as catalyst to degrade ozone and release molecular oxygen. CFCs have permanent and continued effect as chloride atoms are not consumed. This leads to thinning of ozonic layer that has resulted in the formation of ozone hole as observed over the Antarctica region.