During reaction mechanism...
A. catalyst does not change the reaction mechanism.
B. catalyst changes the reaction mechanism.
C. catalyst always makes a reaction mechanim more complicated.
Catalysts lower the activation energy and provide alternative pathways to increase the rate of reaction. So A can't be right. But both B and C can be. I suspect B is the answer your prof wants but the mechanism COULD be more complicated. I suppose the secret word in C is "always". Perhaps it isn't always more complicated.
You are correct in your analysis. Let me break down the options for you:
A. Catalyst does not change the reaction mechanism: This statement is not accurate. Catalysts can indeed change the reaction mechanism by providing an alternative pathway with lower activation energy. This allows the reaction to occur more readily and at a faster rate.
B. Catalyst changes the reaction mechanism: This statement is true. Catalysts work by providing an alternative reaction pathway, which may involve different intermediate steps compared to the uncatalyzed reaction. The catalyst interacts with the reactants and facilitates the formation of an unstable intermediate, which then proceeds to form the desired products.
C. Catalyst always makes a reaction mechanism more complicated: This statement is not entirely accurate. While it is true that catalysts can make the reaction mechanism more complex by introducing additional intermediate steps, it is not always the case. In some instances, catalysts can simplify the reaction mechanism by bypassing slow or unfavorable steps, leading to a more direct and efficient pathway.
In summary, the correct answer would be B: Catalyst changes the reaction mechanism. However, it is important to note that in certain cases, a catalyst may simplify the reaction mechanism rather than making it more complicated.