Hydrogen peroxide is decomposed in the presence of manganese dioxide `(MnO_(2))`.

Explanation

When hydrogen peroxide is decomposed in the presence of manganese dioxide `(MnO_(2))` water and oxygen are formed .
`underset("Hydrogen peroxide")(2H_(2)O_(2_((g))))+underset(Delta)overset(MnO_(2))rarr2H_(2)O_((1))+underset("oxygen")(O_(2))`