JEE Main 2014 · 11 Apr · Shift 1 · Chemistry Q44

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ChemistrySingle correct+4 / -1Question 44 of 90

Which of the following statements about the depletion of ozone layer is correct ?

The problem of ozone depletion is less serious at poles because

\ce{NO2}

solidifies and is not available for consuming

\ce{ClO^.}

radicals.

The problem of ozone depletion is more serious at poles because ice crystals in the clouds over poles act as catalyst for photochemical reactions involving the decomposition of ozone by

\ce{Cl^.}

and

\ce{ClO^.}

radicals.

Freons, chlorofluorocarbons, are inert chemically, they do not react with ozone in stratosphere.

Oxides of nitrogen also do not react with ozone in stratosphere.

Answer and worked solution

Official answer: B

Polar stratospheric clouds (ice crystals) catalyse the conversion of reservoir species into active $\ce{Cl^.}$ and $\ce{ClO^.}$ radicals. That is why depletion is worst over the poles.

The other statements are wrong:

CFCs are broken down by UV and release Cl.
Oxides of nitrogen do react with $\ce{O3}$ .

Topics:Atmospheric pollution

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JEE Main 2014 · 11 Apr · Shift 1, Chemistry question 44