Question

ASSERTION
A catalyst remains unchanged in composition and quantity at the end of the reaction.
REASON
Catalysts are sometimes very specific in respect of reaction.
A.If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
B.If both Assertion and Reason are correct, but Reason is not the correct explanation for Assertion.
C.If Assertion is correct, but Reason is incorrect.
D.If Assertion is incorrect, but Reason is correct.

Answer 1

Hint: Catalysts are the substance that increases the rate of a reaction without itself undergoing any change. A catalyst takes part in the chemical reaction even though they themselves are not consumed or used up during the course of the reaction.

Complete step by step answer:
Catalyst increases the rate of any chemical reaction in which it is involved by forming reaction intermediates that have lower energy also known as transition state and thereby alters the rate of reaction. This intermediate form is short lived and at the end of reaction it breaks into products and regenerates the catalyst.
In a chemical reaction, when reactants are changed into products, activation energy is required. It is defined as the minimum amount of energy required to change the products into the reactants. During catalyst reactions this activation energy is lowered by the catalyst involved and the rate of reaction is increased.
The point at which the reactants involved are not completely reactants or products is known as transition state, and by lowering the energy level of this state rate of reaction is increased as it lowers the activation energy of the reaction.
Catalytic reactions are specific in nature, the catalyst involved in certain reactions would be ineffective in other reactions when added.
Thus, both Assertion and reason are correct but reason is not the correct explanation to assertion.

Hence, option (B) is correct.


Note:
Catalyst can be a chemical or a biological molecule. In our body the role of catalyst is played by enzymes present in our body. These enzymes, which are protein in nature, also increase the rate of reaction occurring inside the body without itself undergoing any change. Example: Hydrolase, Lyase, Lipase etc.