Question

Assertion: Catalyst can increase that rate constant to a large extent
Reason: By using suitable catalyst, we can significantly increase yield
(A) Both assertion and reason are correct and reason is the correct explanation for assertion
(B) Both assertion and reason are correct but reason is not the correct explanation for assertion
(C) Assertion is correct but reason is incorrect
(D) Assertion is incorrect but reason is correct

Answer 1

To answer this question, you must recall the function and properties of a catalyst. A catalyst speeds up a reaction by changing the activation energy of the reaction. The formation of the product can be done faster when the reactants react using an alternative pathway having lower energy.

Complete step by step solution
We know that a catalyst is a substance that when added to a reaction mixture, helps the reaction to proceed in the forward direction without itself being used up. In other words, we can say that the catalyst causes an increase in the rate of the chemical reaction. The catalyst does not cause any change in the mass or composition of the product formed and does not hinder the formation of the product. It works by changing the activation energy of the reaction. The rate constant of a reaction is known to be directly proportional to its rate. Thus, a catalyst can increase the rate constant of the reaction as well.
The catalyst helps the reactant particles to orient in such a way so as to make them collide successfully causing a more effective reaction and forming an intermediate species that is of a lower energy level than the one made originally in the absence of the catalyst. The catalyst has no effect on the yield of the reaction.
Thus, the assertion is a correct statement but the reason is not one.
The correct answer is C.

Note:
A catalyst may not always necessarily increase the rate of the reaction. It may also cause the rate to decrease in some cases and this is known as negative catalysis.