Hint: Chemical properties of hydrogen peroxide 

 Hydrogen peroxide acts as an oxidizing as well as a reducing agent in both acidic and alkaline mediums.

The reactions are as follows:

(i) Oxidising action in acidic medium 

\(2Fe^{2+} (aq) + 2H^+ (aq) + H_2O_2 (aq) \rightarrow 2Fe^{3+} (aq) + 2H_2O (l)\\ PbS(s) + 4H_2O_2 (aq) \rightarrow PbSO_4 (s) + 4H_2O (l)\)

(ii) Reducing action in acidic medium 

\(\begin{aligned} &2 \mathrm{MnO}_{4}^{-}+6 \mathrm{H}^{+}+5 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{Mn}^{2+}+8 \mathrm{H}_{2} \mathrm{O}+5 \mathrm{O}_{2} \\ &\mathrm{HOCl}+\mathrm{H}_{2} \mathrm{O}_{2} \rightarrow \mathrm{H}_{3} \mathrm{O}^{+}+\mathrm{Cl}^{-}+\mathrm{O}_{2} \end{aligned}\)

(iii) Oxidising action in basic medium

\(\begin{aligned} &2 \mathrm{Fe}^{2+}+\mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{Fe}^{3+}+2 \mathrm{OH}^{-} \\ &\mathrm{Mn}^{2+}+\mathrm{H}_{2} \mathrm{O}_{2} \rightarrow \mathrm{Mn}^{4+}+2 \mathrm{OH}^{-} \end{aligned}\)
(iv) Reducing action in basic medium 

\(I_2 + H_2O_2 + 2OH^- \rightarrow 2I^- + 2H_2O + O_2 \\ 2MnO^-_4 + 3H_2O_2 \rightarrow 2MnO_2 + 3O_2 + 2H_2O + 2 OH^-\)