Finer particles make reactions go much [?] than larger particles. This is because the particles have a much bigger area exposed to the reaction mixture. Since the reaction only happens on the surface, the bigger the surface area, the chance of a collision.

We have the same [?] of the reactants, but one experiment uses big particles, while the other experiment uses particles. The [?] of the reaction is higher with the small particles, but the two experiments will give the amount of product in the end.

The rate of reaction is to start off with. Then it gets lower as there are fewer particles, making the chance of a successful collision less likely. The graph is a steep curve, which flattens out.