	List-I (Solid salt treated with dil. $H_{2} {SO}_{4}$ )		List-II (Anion detected)
			List-II (Anion detected)
A.	Effervescence of colourless gas	I.	${NO}_{2}^{-}$
B.	Gas with smell of rotten egg	II.	${CO}_{3}^{2 -}$
C.	Gas with pungent smell	III.	$S^{2 -}$
D.	Brown fumes	IV.	${SO}_{3}^{2 -}$

Experiment	Observation		Anion detected
Solid salt + dil. $H_{2} {SO}_{4}$	A.	Effervescence of colourless and odourless gas which turns lime water milky.	(II) ${CO}_{3}^{2 -}$ is confirmed.
	B.	Colourless gas with rotten egg smell and turns lead acetate paper black.	(III) $S^{2 -}$ is confirmed.
	C.	Colourless gas with pungent smell. Heat and pass the gas through acidified $K_{2} {Cr}_{2} O_{7}$ solution.	(IV) ${SO}_{3}^{2 -}$ is confirmed.
	D.	Colourless gas followed by brown gas (Brown fumes) and it turns ferrous sulphate solution black.	(I) ${NO}_{2}^{-}$ is confirmed.

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