A white precipitate X is insoluble in dilute nitric acid but dissolves in hot concentrated ammonium acetate solution. The resulting solution gives a yellow precipitate with potassium chromate. X is

Answer: B

PbSO X_{4}

dissolves in ammonium acetate because lead(II) acetate complexes are only weakly dissociated; the solution then gives yellow

PbCrO X_{4}

with chromate.

BaSO X_{4}

does not dissolve in ammonium acetate, and

CaSO X_{4}

and

Ag X_{2} SO X_{4}

do not fit the yellow chromate test (Ca gives none, Ag gives brick-red

Ag X_{2} CrO X_{4}

). So X is

PbSO X_{4}