Give the symbolic representation of the following half-cells (electrodes):
$(i)$ $2H^{+}_{(aq)} + 2e^- \to H_{2_{(g)}}$
$(ii)$ $Br_{2_{(aq)}} + 2e^- \to 2Br^{-}_{(aq)}$
$(iii)$ $2Br^{-}_{(aq)} \to Br_{2_{(aq)}} + 2e^-$

The symbolic representation of a half-cell is written as $\text{Electrode} | \text{Electrolyte}$ for oxidation and $\text{Electrolyte} | \text{Electrode}$ for reduction.
$(i)$ $2H^{+}_{(aq)} + 2e^- \to H_{2_{(g)}}$ represents a reduction half-cell involving a gas electrode: $H^{+}_{(aq)} | H_{2_{(g)}} | Pt_{(s)}$.
$(ii)$ $Br_{2_{(aq)}} + 2e^- \to 2Br^{-}_{(aq)}$ represents a reduction half-cell involving a non-metal electrode: $Br_{2_{(aq)}} | Br^{-}_{(aq)} | Pt_{(s)}$.
$(iii)$ $2Br^{-}_{(aq)} \to Br_{2_{(aq)}} + 2e^-$ represents an oxidation half-cell involving a non-metal electrode: $Pt_{(s)} | Br^{-}_{(aq)} | Br_{2_{(aq)}}$.