(i) Name the acid used for the preparation of hydrogen chloride gas in the laboratory. Why is this particular acid preferred to other acids?

(i) Conc. H₂SO₄ is used for the preparation of hydrogen chloride gas in the laboratory.

As conc. H₂SO₄ is non-volatile and has a high boiling point, therefore, it displaces the volatile hydrogen chloride from the salt sodium chloride. Hence, conc. H₂SO₄ is used as a reactant in the laboratory preparation of HCl from sodium chloride.

(ii) $\text{NaCl} + \text{H}_2\text{SO}_4 \xrightarrow{\lt 200 ^{\circ}\text{C}} \text{NaHSO}_4 + \text{HCl [g.]}$