Question

When a student heated a colourless solid compound, then brown fumes of a gas are evolved. The colourless solid is most likely to be :
(1) ferrous sulphate
(2) lead carbonate
(3) lead nitrate
(4) lead sulphate

Answer 1

When lead nitrate is heated it splits into simpler substances,
$\underset{\mathrm{Colourless}}{2\mathrm{Pb}({\mathrm{NO}}_3{)}_2}\to \underset{\mathrm{Yellow}}{2\mathrm{PbO}}+\underset{\mathrm{Brown}}{4{\mathrm{NO}}_2}+{\mathrm{O}}_2$
NO₂ gas imparts brown fumes to the solution.

Hence, the correct answer is option 3.