Which of the following correctly describe the behaviour of H2S gas liberated from sulphide with dilute acid?

It blackens paper moistened with lead acetate because PbS forms

It turns acidified K2Cr2O7 paper green with deposition of sulphur

It gives a black precipitate with aqueous CuSO4

It blackens paper moistened with lead acetate because PbS forms

It turns acidified K2Cr2O7 paper green with deposition of sulphur

It gives a black precipitate with aqueous CuSO4

It gives a white milky precipitate of CaS with lime water

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3qa184

Which of the following correctly describe the behaviour of $H X_{2} S$ gas liberated from sulphide with dilute acid?

AIt blackens paper moistened with lead acetate because $PbS$ forms
BIt turns acidified $K X_{2} Cr X_{2} O X_{7}$ paper green with deposition of sulphur
CIt gives a black precipitate with aqueous $CuSO X_{4}$
DIt gives a white milky precipitate of $CaS$ with lime water

H X_{2} S + Pb (CH X_{3} COO) X_{2} PbS + 2 CH X_{3} COOH

and

CuS

are both black.

Cr X_{2} O X_{7} X^{2 -} + 3 H X_{2} S + 8 H X^{+} 2 Cr X^{3 +} + 3 S + 7 H X_{2} O

gives green

Cr X^{3 +}

and sulphur. Lime water simply absorbs

H X_{2} S

to give soluble

Ca (HS) X_{2}

CaS

(hydrolysed), not a milky precipitate.