JEE Main · 2021 · 18 Mar 2021 · Shift 2 · Hydrogen

In alkaline solution hydrogen peroxide acts both ways. Towards manganese(II) it is the oxidant, $\mathrm{M}{\mathrm{n}}^{2+}+{\mathrm{H}}_2{\mathrm{O}}_2⟶\mathrm{M}{\mathrm{n}}^{4+}+2\mathrm{O}{\mathrm{H}}^{-}$, and towards iodine it is the reductant, ${\mathrm{I}}_2+{\mathrm{H}}_2{\mathrm{O}}_2+2\mathrm{O}{\mathrm{H}}^{-}⟶2{\mathrm{I}}^{-}+2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$. Oxidation of lead sulphide to lead sulphate is the acidic-medium reaction of hydrogen peroxide and does not belong here. The conversions it brings about in basic medium are $\mathrm{M}{\mathrm{n}}^{2+}\to \mathrm{M}{\mathrm{n}}^{4+}$ and ${\mathrm{I}}_2\to {\mathrm{I}}^{-}$ only.