Answer:
Smashing the cube into pieces
Explanation:
The reason for this is that if we were to smash the cube we would have a larger surface area which means more manganese oxide would be dissolving per second which means we would have a faster reaction rate where if we were to chill the peroxide it would dissolve slower which in turn slows the reaction. For example a spoonful of granulated sugar will react with water faster than a sugar cube.
