Which statement about reaction rates is true? (A) Changing the temperature cannot speed up a reaction rate. (B) Changing the amount of reactants will not change the reaction rate. (C) Changing the surface area affects the reaction rate. (D) A catalyst slows down the reaction rate.

C

Explanation:

Let's start with the equation for the reaction rate V = k [A]^a [B]^b, this constant k has it's on reaction which will have temperature on it.

A) Yes, if you change the mperature the reaction can speed up, as well as slow down.

B) The reactants concentration is as integral part of the equation, os it will also change de reaction rate.

C) Changing the surface area, there will be more reactant ready to react, so the reaction rate will be affect.

D) Catalysts have the fuction to lower the energy needed so the reaction will occur, so it will speed up.

(C) Changing the surface area affects the reaction rate.