Question

The statement that is not true about ozone is:

• A. It is a toxic gas and its reaction with $NO$ gives $N{O}_2$
• B. in the stratosphere, it forms a protective shield against UV radiation.
• C. in the atmosphere, it is depleted by CFCs.
• D. in the stratosphere, CFCs release chlorine free radicals $\left(Cl\right)$ which reacts with $O_3$ to give chlorine dioxide radicals.

Answer 1

The correct option is D in the stratosphere, CFCs release chlorine free radicals $\left(Cl\right)$ which reacts with $O_3$ to give chlorine dioxide radicals.

In presence of sunlight CFC's molecule divides & release chlorine free radical, which react with ozone give chlorine monoxide radical $\left(Cl{O}^{\cdot }\right)$

$C{F}_{2}C{l}_2\left(g\right)\stackrel{UV}{\to }\stackrel{\bullet }{C}l\left(g\right)+\stackrel{\bullet }{C}{F}_{2}Cl\left(g\right)$

$\stackrel{\bullet }{C}l\left(g\right)+O_3\left(g\right)\to Cl{O}^{\bullet }\left(g\right)+O_2\left(g\right)$

$Cl{O}^{\bullet }\left(g\right)+O\left(g\right)\to C{l}^{\bullet }\left(g\right)+O_2\left(g\right)$