How is sulphur dioxide prepared in laboratory?

Complete the following equation:

${\mathrm{Na}}_2{\mathrm{SO}}_3+2\mathrm{HCl} \stackrel{ }{\to } 2\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O} + \mathrm{\_\_\_}$ 

Complete the following equation:

${\mathrm{Na}}_2{\mathrm{SO}}_3+2\mathrm{HCL}\to 2\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}+\dots \dots$

Complete the following reaction, and balance it.

${\mathrm{Na}}_2{\mathrm{SO}}_3\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)\stackrel{ }{\to }$

An aqueous solution of gas $‘\mathrm{A}’$ gave the following reactions.

(i) It decolourised an acidified ${\mathrm{KMnO}}_4$ solution.

(ii) On boiling with ${\mathrm{H}}_2{\mathrm{O}}_2$ followed by cooling and then adding an aqueous solution of ${\mathrm{BaCl}}_2$, a white precipitate insoluble in dil. $\mathrm{HCl}$ was obtained,

Identify the gas ‘A’ and give the equation for step (ii).

Explain the following with the help of balanced chemical equation:

Bleaching action of ${\mathrm{SO}}_2$