Select the correct statement(s) about the solubility of sparingly soluble salts at constant temperature.

A $ZnS$ is more soluble in dilute $HCl$ than in pure water
B $AgCl$ is more soluble in $0.1 M$ $NaCl$ than in pure water, because of the extra $Cl X^{-}$
C $Ag X_{2} CrO X_{4}$ is equally soluble in $0.1 M$ $HNO X_{3}$ and in pure water
D $AgCl$ is more soluble in $1 M$ $NH X_{3}$ than in pure water

Answer: A, D

S X^{2 -}

is a strong base toward

H X^{+}

(forming

HS X^{-}

and

H X_{2} S

), so

ZnS

dissolves better in acid.

Cl X^{-}

from

NaCl

is a common ion for

AgCl

and lowers its solubility, so the second statement is false.

CrO X_{4} X^{2 -}

is protonated to

HCrO X_{4} X^{-}

in acid, so

Ag X_{2} CrO X_{4}

is more soluble in

HNO X_{3}

; the third statement is false.

NH X_{3}

forms

[Ag (NH X_{3}) X_{2}] X^{+}

, increasing the solubility of

AgCl