Question

which statement about catalysts is true? catalysts increase the activation energy required for the reaction. catalysts always change states of matter during the reaction. catalysts are not used up during the reaction. catalysts slow down the rate of reaction.

Explanation:

• Analyze the first option: Catalysts lower activation energy, not increase it. So this is false.
• Analyze the second option: Catalysts don't always change states of matter. For example, in some reactions, solid catalysts remain solid. So this is false.
• Analyze the third option: By definition, catalysts are substances that increase the rate of a reaction without being consumed (used up) in the process. This is a key property of catalysts.
• Analyze the fourth option: Catalysts increase the rate of reaction (positive catalysts) or can decrease (negative catalysts, but the common understanding of catalysts in basic chemistry is as positive catalysts that speed up reactions). The statement says they slow down, which is incorrect for typical catalysts.

Answer:

C. Catalysts are not used up during the reaction.