Question

Choose the correct answer from the options given below:
(i) Hydroxide of this metal is soluble in sodium hydroxide solution.
(a) Magnesium
(b) Lead
(c) Silver
(d) Copper

(ii) When dilute sulphuric acid reacts with iron sulphide, the gas evolved is ________.
(a) Hydrogen sulphide
(b) Sulphur dioxide
(c) Sulphur trioxide
(d) Vapour of sulphuric acid.

Answer 1

(i) (b) lead

Lead hydroxide is soluble in excess sodium hydroxide solution because it forms colourless complex sodium plumbite.
$\mathrm{Zn}{\left(\mathrm{OH}\right)}_2+2\mathrm{NaOH}\to {\mathrm{Na}}_2\left[\mathrm{Zn}{\left(\mathrm{OH}\right)}_4\right]$

(ii) (a) hydrogen sulphide

Dilute sulphuric acid reacts with iron sulphide to form ferrous sulphate salt and release hydrogen sulphide gas having foul odour of rotten eggs.
$\mathrm{FeS}+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{FeSO}}_4+{\mathrm{H}}_2\mathrm{S}$