Question 46: Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :
Assertion A : A reaction can have zero activation energy.
Reasons R : The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to threshold value, is called activation energy.
In the light of the above statements, choose the correct answer from the options given below :
(1) \mathbf{A} is true but \mathbf{R} is false.
(2) \mathbf{A} is false but \mathbf{R} is true.
(3) Both \mathbf{A} and \mathbf{R} are true and \mathbf{R} is the correct explanation of \mathbf{A}.
(4) Both \mathbf{A} and \mathbf{R} are true and \mathbf{R} is NOT the correct explanation of \mathbf{A}.
Answer: Option (2)
Explanation:
Assertion A states that a reaction can have zero activation energy.
This statement is false for chemical reactions at the molecular level, because reactant molecules must cross an energy barrier known as activation energy to reach the activated complex.
Reason R correctly defines activation energy as the minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to the threshold energy.
Since Reason R is a correct definition of activation energy, it is true.
However, Assertion A is false, while Reason R is true. Therefore, the correct option is Option (2).