Which statement about reaction rates is true? changing the surface area affects the reaction rate. changing the temperature cannot speed up a reaction rate. changing the amount of reactants will not change the reaction rate. a catalyst slows down the reaction rate.

The answer to your question is A.

Explanation: The other user who answered this was incorrect however it could have just been a mistake. But a catalyst speeds up the reaction rate. :) The reason the answer is A is because Increasing the surface area of a solid reactant exposes more of its particles to attack. This results in an increased chance of collisions between reactant particles, so there are more collisions in any given time and the rate of reaction increases.

I hope this helps you out lots! :D