: Which is/are correct statements regarding the correct role of catalyst in a reaction?
A.It is a reactant in a rate determining step and then a product of some subsequent step.
B.It provides an alternate mechanism with a lower energy of activation.
C.It increases the rate of chemical reaction but does not itself undergo a permanent change during the course of the reaction.
D.Enzyme catalysts are protein molecules
E.All of the above.

Hint:A catalyst is a chemical entity that enhances the rate of a chemical or biological reaction, but itself remains neutral or does not participate in the reaction. It does not change the value of equilibrium, it just decreases the time required to achieve equilibrium.

Complete step by step answer:
A catalyst is a substance which increases the rate of the chemical reaction without being consumed. And hence they affect the rate determining step. So the first statement is true in this regard.
A catalyst can drive a chemical or a biological reaction through a different route for which the activation energy of the reaction is low and hence the reaction is completed in time. so this statement is also true.
The function of the catalyst is to enhance the rate of the reaction without undergoing any change itself. Hence this statement is also correct.
Enzymes are a class of catalysts that are responsible for facilitating and improving the rate of the biochemical reactions in plants and animals. They are complex protein molecules.

All the statements in this regard being true, option E is the correct answer.

Note:
A catalyst does not alter the position of equilibrium of a reaction, which the magnitude of equilibrium, it just lowers the time required to attain the equilibrium. The catalysts can also slow down a rate of reaction, in that case it is known as an “inhibitor”. Sometimes, a compound is also added along with the catalyst to increase and decrease its activity. This is also known as promoters and poisons respectively.