${\mathrm{MnO}}_4^{-}$ oxidizes ${\mathrm{H}}_2{\mathrm{O}}_2 \mathrm{to} {\mathrm{O}}_2$ in acidic medium

${\mathrm{xMnO}}_4^{-} + {\mathrm{yH}}_2{\mathrm{O}}_2 + {\mathrm{zH}}^{+} \stackrel{ }{\to } {\mathrm{Mn}}^{2+} + {\mathrm{O}}_2 + {\mathrm{H}}_2\mathrm{O}$

Coefficients x, y and z are respectively

Cross-multiply by change in oxidation number and balanced H by ${\mathrm{H}}^{+}$ ions.

$2{\mathrm{MnO}}_4^{-} + 5{\mathrm{H}}_2{\mathrm{O}}_2 + 6{\mathrm{H}}^{+} \stackrel{ }{\to } 2{\mathrm{Mn}}^{2+} + 5{\mathrm{O}}_2 + 8{\mathrm{H}}_2\mathrm{O}$

Thus, x = 2, y = 5 and z = 6.