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):

So, the right choice is:

Manganese dioxide is a catalyst.

Manganese dioxide is a catalyst

Explanation:

Just took the test :)

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".