In which of the following reactions H₂O₂ acts as reducing agent?

$\left(\mathrm{i}\right) {\mathrm{H}}_2{\mathrm{O}}_2+2{\mathrm{H}}^{+}+2{\mathrm{e}}^{-}\stackrel{ }{\to }2{\mathrm{H}}_2\mathrm{O}$

$\left(\mathrm{ii}\right){\text{ H}}_2{\mathrm{O}}_2-2{\mathrm{e}}^{-}\stackrel{ }{\to }{\mathrm{O}}_2+2{\mathrm{H}}^{+}$

$\left(\mathrm{iii}\right){\text{ H}}_2{\mathrm{O}}_2+2{\mathrm{e}}^{-}\stackrel{ }{\to }2{\mathrm{OH}}^{-}$

$\left(\mathrm{iv}\right){\text{ H}}_2{\mathrm{O}}_2+2{\mathrm{OH}}^{-}-2{\mathrm{e}}^{-}\stackrel{ }{\to }{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$