A catalyst is:
A. a solid product of a reaction.
B. one of the reactants in a single-replacement reaction.
C. not used up in a reaction.
D. the product of a combustion reaction.
C?
Yes, you are correct. A catalyst is not used up in a reaction, so the correct answer is C.
To determine this, we need to understand the definition and role of a catalyst. A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative pathway with lower activation energy. It achieves this by lowering the energy barrier for the reaction, enabling the reactants to be converted into products more easily. However, at the end of the reaction, the catalyst remains unchanged and can be used again in subsequent reactions. It does not undergo any significant chemical change or get consumed during the reaction, which is why option C is the correct answer.