Write chemical reactions to justify that hydrogen peroxide $(H_{2}O_{2})$ can function as an oxidising as well as a reducing agent.

(N/A) Hydrogen peroxide acts as an oxidising as well as a reducing agent in both acidic and alkaline media. The reactions are as follows:
$(i)$ Oxidising effect in acidic medium:
$2 Fe^{2+}_{(aq)} + 2 H^{+}_{(aq)} + H_{2}O_{2(aq)} \longrightarrow 2 Fe^{3+}_{(aq)} + 2 H_{2}O_{(l)}$
$PbS_{(s)} + 4 H_{2}O_{2(aq)} \longrightarrow PbSO_{4(s)} + 4 H_{2}O_{(l)}$
$(ii)$ Reducing effect in acidic medium:
$2 MnO_{4}^{-} + 6 H^{+} + 5 H_{2}O_{2} \longrightarrow 2 Mn^{2+}_{(aq)} + 8 H_{2}O + 5 O_{2}$
$HOCl + H_{2}O_{2} \longrightarrow H_{3}O^{+} + Cl^{-} + O_{2}$
$(iii)$ Oxidising effect in basic medium:
$2 Fe^{2+} + H_{2}O_{2} \longrightarrow 2 Fe^{3+} + 2 OH^{-}$
$Mn^{2+} + H_{2}O_{2} \longrightarrow Mn^{4+} + 2 OH^{-}$
$(iv)$ Reducing effect in basic medium:
$I_{2} + H_{2}O_{2} + 2 OH^{-} \longrightarrow 2 I^{-} + 2 H_{2}O + O_{2}$
$2 MnO_{4}^{-} + 3 H_{2}O_{2} \longrightarrow 2 MnO_{2} + 3 O_{2} + 2 H_{2}O + 2 OH^{-}$