i. Hydrogen + Chlorine → Hydrogen chloride

: A balanced equation consists of the same number of moles on the reactants and the products side. The balanced equation for the given reaction is: \[H_2{}_{(g)} + Cl_2{}_{(g)} \rightarrow 2HCl{}_{(g)}\]

ii. Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride

: A balanced equation consists of the same number of moles on the reactants and the products side. The balanced equation for the given reaction is: \[3BaCl_2{}_{(s)} + Al_2(SO_4)_3{}_{(s)} \rightarrow 3BaSO_4{}_{(s)} + 2AlCl_3{}_{(s)}\]

iii. Sodium + Water → Sodium hydroxide + Hydrogen

: A balanced equation consists of the same number of moles on the reactants and the products side. The balanced equations for the given reaction is: \[
2Na{}_{\mathrm{(s)}} + 2H_2O{}_{\mathrm{(l)}} \rightarrow 2NaOH{}_{\mathrm{(aq)}} + H_2{}_{\mathrm{(g)}}
\]