Which statement about catalysts in chemical reactions is true?

• A. They are consumed and increase the rate
• B. They are not consumed and increase the rate
• C. They decrease the rate
• D. They have no effect on rate

Answer: (B)

Catalysts work by providing an alternative reaction pathway that requires a lower activation energy, which speeds up the reaction. They are not consumed in the overall process, so they emerge unchanged after the reaction, ready to catalyze more events. Lower activation energy means more molecules have enough energy to react at a given temperature, so the rate constant increases and the reaction proceeds faster. Importantly, while a catalyst speeds up both the forward and reverse reactions, it doesn’t change the final balance of products and reactants—the equilibrium position is determined by thermodynamics, not by the catalyst.

So the true statement is that a catalyst increases the rate without being consumed. The other ideas—being consumed, decreasing the rate, or having no effect—do not describe how catalysts function.