Match the pollutant in Column I with its characteristic effect or property in Column II. Column I: (P) $CO$ ; (Q) $SO X_{2}$ ; (R) PAN; (S) $NO X_{2}$ . Column II: (1) irritates eyes in photochemical smog; (2) forms a stable complex with haemoglobin; (3) reddish brown gas that gives a brown haze; (4) forms $H X_{2} SO X_{4}$ in rain after oxidation.

Answer: A

CO

gives carboxyhaemoglobin (2).

SO X_{2}

is oxidised to

SO X_{3}

and then

H X_{2} SO X_{4}

(4). PAN is the eye irritant of photochemical smog (1).

NO X_{2}

is reddish brown and gives the brown haze (3). So P-2, Q-4, R-1, S-3.