(i) Hydrogen + Chlorine → Hydrogen chloride
(ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
(iii) Sodium + Water → Sodium hydroxide + Hydrogen
Here are the balanced chemical equations for the given reactions:
(i) Hydrogen + Chlorine → Hydrogen chloride
\[
\text{H}_2 + \text{Cl}_2 \rightarrow 2\text{HCl}
\]
(ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
\[
3\text{BaCl}_2 + \text{Al}_2(\text{SO}_4)_3 \rightarrow 3\text{BaSO}_4 + 2\text{AlCl}_3
\]
(iii) Sodium + Water → Sodium hydroxide + Hydrogen
\[
2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2
\]
Both reactions are now balanced with respect to the number of atoms of each element on both sides.