In which of the following reactions, hydrogen peroxide acts as an...

The reaction in which ${H}_{2}{O}_{2}$ is getting reduced, it will behave as oxidising agent.

$2{\text{e}}^{-} + 2{\text{H}}^{+} + {\text{H}}_{2}{\text{O}}_{2} ⟶ 2{\text{H}}_{2}\text{O} ( \text{r}\text{e}\text{d}\text{u}\text{c}\text{t}\text{i}\text{o}\text{n} )$

${\text{S}}^{- 2} + 4{\text{H}}_{2}\text{O} ⟶ \text{S}{\text{O}}_{4}^{- 2} + 8{\text{H}}^{+} + 8{\text{e}}^{-} ( \text{o}\text{x}\text{i}\text{d}\text{a}\text{t}\text{i}\text{o}\text{n} )$

\left(\text{E}\text{q}\text{u}\text{a}\text{t}\text{i}\text{o}\text{n} . 1 \times 4\right) + \left(\text{E}\text{q}\text{u}\text{a}\text{t}\text{i}\text{o}\text{n} . 2\right)$<br /><br />$\text{F}\text{i}\text{n}\text{a}\text{l}\text{r}\text{e}\text{a}\text{c}\text{t}\text{i}\text{o}\text{n}\text{P}\text{b}\text{S} + 4{\text{H}}_{2}{\text{O}}_{2} ⟶ \text{P}\text{b}\text{S}{\text{O}}_{4} + 4{\text{H}}_{2}\text{O}$