Which of the following is TRUE of a catalyst?

41. Which of the following is TRUE of a catalyst?

I. it alters the activation energy of a

reaction.

II. it is effective in a reaction but cannot

initiate a reaction.

III. it affects the equilibrum of a reversible reaction.

IV. it affects the overall reaction.

A. I and II only

B. I, II and Ill only

C. II and III only

D. II, III and IV only

E. III and IV only

The correct answer is A. I and II only

Explanation: A catalyst is a substance that speed up (or slow down) the rate of a chemical reaction and remain unchanged at the end of the reaction. We have positive catalyst which speed up a chemical reaction and negative catalyst which slow down a chemical reaction. Finely divided iron is employed in the haber process for the production of ammonia. Zymase is employed in the fermentation of glucose to produce alcohol etc. It is worthy of note that a catalyst does not affects the equilibrium of a reversible reaction. It also does not affect the overall reaction.

Question source: 2001 NECO OBJECTIVE QUESTION 41. 

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