Which property of manganese dioxide it turn hydrogen peroxide into water faster than it would without it? manganese dioxide is an acid. manganese dioxide is a catalyst. manganese dioxide is highly reactive. manganese dioxide is used up very fast.

Manganese dioxide is a catalyst.

Explanation:

The decomposition of hydrogen peroxide into water and oxygen is a slow reaction and MnO₂ is used as a catalyst to speed up the reaction.

The role of MnO₂ (catalyst):

Chemical reactions occur faster in the presence of a catalyst because the catalyst provides an alternative reaction pathway with a lower activation energy than the non-catalyzed mechanism. In catalyzed mechanisms, the catalyst usually reacts to form a temporary intermediate, which then regenerates the original catalyst in a cyclic process. A substance which provides a mechanism with a higher activation energy does not decrease the rate because the reaction can still occur by the non-catalyzed route.The catalyst does not used up in the reaction.

So, the right choice is:

Manganese dioxide is a catalyst.