Which of the following statements about catalysis is correct? (1). A small amount of catalyst often affects the rate of a reaction for a long time (2). a catalyst is always chemically unchanged at the end of a reaction (3). The effect of a catalyst is often enhanced by adding promoters (4). A catalyst always physically unchanged at the end of a reaction catalyst always speeds up the rate of a chemical reaction
A. 1,2,3,4,5 B. 1,2,3 C. 2,3,4 only D. 2,4,only
Correct Answer: B
Explanation
A catalyst does not undergo a permanent chemical change. It may, however, undergo a physical change.lso, note that only a positive catalyst speeds up the rate of a chemical reaction; a negative one slows it down. An example of negative catalyst is phosphoric acid, which is used to slow down the rate at which \(\mathrm{H}_2 \mathrm{O}_2\) (hydrogen peroxide) decomposes.
