NEETChemistryChemical Kinetics
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): For a reaction with zero activation energy, the plot of k versus 1 T is a straight line passing through the origin. Reason (R): For a reaction with zero activation energy, the rate constant is independent of temperature. In the light of the above statements, choose the most appropriate answer from
Options
- ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- CAssertion (A) is true but Reason (R) is false.
- DAssertion (A) is false but Reason (R) is true.
Correct answer
D. Assertion (A) is false but Reason (R) is true.
Step-by-step solution
According to the Arrhenius equation, k = A e^ - E_a RT . For a reaction with zero activation energy ( E_a = 0 ), the equation becomes k = A e^0 = A . This shows that the rate constant k is independent of temperature, making Reason (R) true. Taking the natural logarithm, we get k = A . The plot of k versus 1 T will be a horizontal straight line with a slope of zero and a y-intercept of A . It will not pass through the origin (unless A=1 , which is not a general case). Therefore, Assertion (A) is false. Answer: Asser