protons because of the atomic number
Answer:
Chilling the hydrogen peroxide solution
Explanation:
The MnO₂ is acting as a catalyst.
Chilling the hydrogen peroxide solution reduces the average kinetic energy of the H₂O₂ molecules.
Fewer of them will have enough kinetic energy to overcome the activation energy of the reaction. The rate will decrease.
A is wrong. Using a larger amount of solution does not increase the number of H₂O₂ molecules that can reach the surface of the catalyst per second. There is no effect on the rate.
B is wrong. Increasing the mass of the cube increases its surface area. More molecules of H₂O₂ can reach the surface of the catalyst per second. The rate increases.
D is wrong. Smashing the cube into pieces vastly increases the surface area, so the rate increases