Two equal samples, each containing 0.0200 mol of Pb^2+, are precipitated completely, one as PbSO4 with dilute H2SO4 and the other as PbCrO4 with K2CrO4 (Pb 207, S 32, Cr 52, O 16). The difference in mass of the two precipitates, and the one that dissolves in hot concentrated ammonium acetate, are

JEE Advanced levelSingle correct optionDifficulty 3 of 3qc054

Two equal samples, each containing $0.0200 mol$ of $Pb X^{2 +}$ , are precipitated completely, one as $PbSO X_{4}$ with dilute $H X_{2} SO X_{4}$ and the other as $PbCrO X_{4}$ with $K X_{2} CrO X_{4}$ (Pb 207, S 32, Cr 52, O 16). The difference in mass of the two precipitates, and the one that dissolves in hot concentrated ammonium acetate, are

M (PbSO X_{4}) = 207 + 32 + 64 = 303

and

M (PbCrO X_{4}) = 207 + 52 + 64 = 323 g mo l^{- 1}

. The difference per mole is

20 g

, so for

0.0200 mol

it is

0.40 g

. White

PbSO X_{4}

dissolves in hot concentrated ammonium acetate (acetato complex formation), whereas yellow

PbCrO X_{4}

does not dissolve in it.