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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3qa218

Which statements about the chromyl chloride test are correct?

ABromides and iodides do not give red vapours of chromyl bromide or chromyl iodide, but are oxidised to $Br X_{2}$ and $I X_{2}$
BThe red vapour $CrO X_{2} Cl X_{2}$ contains chromium in the $+ 6$ state
CThe test is given equally well by $NaCl$ and by $HgCl X_{2}$
DAbsorbing the vapour in $NaOH$ gives yellow $CrO X_{4} X^{2 -}$ , confirmed with lead acetate as yellow $PbCrO X_{4}$

Answer: A, B, D

Chromium in

CrO X_{2} Cl X_{2}

is

+ 6

(

x - 4 - 2 = 0

). Hydrolysis with alkali gives

CrO X_{4} X^{2 -}

, and

CrO X_{4} X^{2 -} + Pb X^{2 +} PbCrO X_{4}

is yellow. Bromide and iodide are oxidised by the dichromate mixture, so only halogen vapour is seen. Covalent

HgCl X_{2}

does not give the test.

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