Which statement describes chemical reactions that take place at different rates? a. one reaction produces more products than the other. b. one reaction begins with more reactants than the other. c. one reaction takes place in less time than the other. d. one reaction involves a color change and the other does not.

Different rates refers to the amount of time it takes for the chemical reaction to take place. Therefore the answer would be C. One reaction takes place in less time than the other.

C. One reaction takes place in less time than the other. Without knowing what reactions are taking place we can't be sure that one does not change color while the other does, which rules out choice D. They could easily produce the same amount of products, just not in the same amount of time, so A is out, too. Both reactions most likely begin with the same amount of reactants, which deleted choice B, leaving only choice C.