MolSynapsequestion bank

MolSynapse / Question bank / Qualitative Analysis: Cations / Confirmatory tests and coloured precipitates

JEE Advanced levelSingle correct optionDifficulty 3 of 3qc155

A white precipitate from dilute $HCl$ dissolves on boiling with water. The hot solution gives a yellow precipitate with $K X_{2} CrO X_{4}$ . Which description of the yellow precipitate is correct?

A $PbCrO X_{4}$ ; soluble in acetic acid, insoluble in $NaOH$
B $PbCrO X_{4}$ ; insoluble in acetic acid, soluble in $NaOH$
C $Hg X_{2} CrO X_{4}$ ; insoluble in acetic acid, soluble in $NaOH$
D $PbCr X_{2} O X_{7}$ ; soluble in acetic acid, insoluble in $NaOH$

Answer: B

The white chloride soluble in hot water is

PbCl X_{2}

(not

AgCl

or

Hg X_{2} Cl X_{2}

), so the cation is

Pb X^{2 +}

.

PbCrO X_{4}

is yellow, insoluble in dilute acetic acid, and dissolves in

NaOH

as plumbite/chromate species. The equations used are

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

.

Practice Qualitative Analysis: Cations More on Confirmatory tests and coloured precipitates

Previous questionNext question

More questions on Confirmatory tests and coloured precipitates