JEE Main 2024 — Practical Chemistry Question with Solution

With warm dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$ a sulphide gives hydrogen sulphide gas which smells like rotten eggs. A piece of filter paper dipped in lead acetate solution turns black on exposure to the gas due to the formation of lead sulphide which is black in colour.

As we know, hydrogen sulphide gas is a colourless gas and when it reacts with lead acetate it produces lead sulphide and acetic acid. The chemical reaction of hydrogen sulphide with lead acetate is given as:

${\mathrm{Na}}_2 \mathrm{S}+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{Na}}_2{\mathrm{SO}}_4+{\mathrm{H}}_2 \mathrm{S}$

$\underset{}{{\left({\mathrm{CH}}_3\mathrm{COO}\right)}_2 \mathrm{Pb}+{\mathrm{H}}_2 \mathrm{S}\to \underset{\mathrm{Black} \mathrm{lead} \mathrm{sulphide}}{\mathrm{PbS}}+2{\mathrm{CH}}_3\mathrm{COOH}}$

Hence, the answer is option C.