Question

In winter, polar stratospheric clouds formed over Antarctica provide surface on which compound X responsible for depletion of ozone is formed. What is X?

• A. Peroxyacetyl nitrate
• B. Acrolein
• C. Chlorine nitrate
• D. Sulphuryl chloride

Hint:

Remember: Antarctic ozone depletion is strongly associated with chlorine radicals generated from chlorine reservoir compounds like chlorine nitrate.

Answer 1

The Correct Option is C

Concept: Ozone depletion in the stratosphere is strongly connected with chlorine-containing compounds derived mainly from chlorofluorocarbons (CFCs). During winter in Antarctica, extremely low temperatures cause the formation of polar stratospheric clouds (PSC). These clouds provide solid surfaces where chemical reactions convert inactive chlorine reservoir species into active ozone-destroying compounds. One important compound formed under these conditions is chlorine nitrate. \[ ClONO_2 \] This compound participates in catalytic ozone destruction cycles.

Step 1: Understand role of polar stratospheric clouds. Polar stratospheric clouds form under very low temperatures in the upper atmosphere. These clouds provide surfaces for heterogeneous chemical reactions. Inactive chlorine compounds get converted into reactive species.

Step 2: Identify chlorine reservoir compounds. Important chlorine reservoir compounds include: \[ HCl,\qquad ClONO_2 \] where \[ ClONO_2 = \text{Chlorine nitrate} \] These participate in ozone depletion chemistry.

Step 3: Analyze options. Peroxyacetyl nitrate is photochemical smog component. Acrolein is organic pollutant. Sulphuryl chloride does not participate significantly in ozone depletion. Only chlorine nitrate is involved. Hence answer is \[ \boxed{ClONO_2} \]