In basic medium, H _ 2 O _ 2 exhibits which of the following...

In basic medium, oxidising action of ${H}_{2}{O}_{2}$.

${Mn}^{2 +} + {H}_{2}{O}_{2} \to {Mn}^{+ 4} + 2{OH}^{-}$

In basic medium, reducing action of ${H}_{2}{O}_{2}$

${I}_{2} + {H}_{2}{O}_{2} + 2{OH}^{-} \to 2{I}^{-} + 2{H}_{2}O + {O}_{2}$

In acidic medium, oxidising action of ${H}_{2}{O}_{2}$

$PbS ( s ) + 4{H}_{2}{O}_{2} ( aq ) \to {PbSO}_{4} ( s ) + 4{H}_{2}O ( l )$

Hence correct option $( 4 )$.