Question

The pollutant responsible for ozone holes is:
(A) $C{O_2}$
(B) $S{O_2}$
(C) $CO$
(D) $CFC$

Answer 1

Hint: Ozone hole is developed after a successive ozone depletion. The pollutant that contributes more for ozone depletion is colourless, tasteless, non-flammable and chemically stable compounds and that is widely used as coolants and propellants.

Complete step by step solution:
Pollutants are agents that cause undesirable changes in the environment. Ozone is a protective layer in the stratosphere of the earth that protects from UV rays that are emitted by the sun. Ozone gas is continuously formed by the action of UV rays on molecular oxygen and destruction into molecular oxygen. This phenomenon of formation and destruction of ozone should be balanced because it prevents the entering of UV rays in the earth's atmosphere.
-Reaction of formation of ozone:
The oxygen is broken into two monatomic oxygen (oxygen free radicals) in presence of UV rays.
 \[{O_2}\xrightarrow{{UVrays}}{O^ \bullet } + {O^ \bullet }\]
The monoatomic oxygen obtained in the above reaction reacts with other oxygen gas to give an ozone molecule.
\[{O^ \bullet } + {O_2} \to {O_3}\]
-Reaction of the destruction of ozone
\[{O_3}\xrightarrow{{UVrays}}{O_2} + {O^ \bullet }\]
The balance between formation and destruction of the ozone layer is disturbed due to enhancement of the process of destruction by pollutants which leads to ozone depletion. Ozone depletion can be defined as the thinning of the ozone layer. The process of successive thinning of the ozone layer leads to an ozone hole through which UV rays enter the earth and affect living organisms. The pollutant that is responsible for depletion is CFC. CFC is a compound based on hydrocarbons where all the hydrogen is replaced by chlorine or fluorine atoms. Let's see how CFC contributes to the enhancement of the destruction of ozone. CFCs are widely used in refrigerants.
-Action of CFC on ozone
The CFC discharged from the environment from refrigerants, air conditioner etc. move upwards and reach the stratosphere where UV rays strike on the CFC it liberates cl or another halide that is compound.
\[CFC\xrightarrow{{UVrays}}C{l^ \bullet } + C{l^ \bullet }\]
The chlorine molecule (chlorine-free radical) discharged in the above reaction reacts with an ozone molecule and gives pure hypochlorite and monatomic oxygen (oxygen free radical).
\[{O_3} + C{l^ \bullet } \to ClO + {O_2}\]

Option D is the correct option. CFC is the pollutant that is responsible for ozone holes.

Note: CFCs are chemically stable and volatile properties are its speciality. CFCs is the correct option. Other options that are $S{O_2}$, $CO$ and $C{O_2}$ are greenhouse gases which are firstly responsible for climate change which consequently leads to global warming.