In the equation, \( k=Ae^{-E_a/RT} \), A is -
A. Arrhenius factor
B. Activated factor
C. Frequency factor
D. pre-exponential factor
E. Order factor
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, C and D only
The Arrhenius equation relates the rate constant to temperature:
\( \displaystyle k=A\,e^{-E_a/RT} \)
(A) Arrhenius factor — Correct. A is the constant of the Arrhenius equation for a given reaction.
(B) Activated factor — Incorrect. No such name is used for A; the related term, the activated complex, is the unstable intermediate at the top of the energy barrier.
(C) Frequency factor — Correct. A is related to the frequency of collisions between reacting molecules.
(D) pre-exponential factor — Correct. This is the name of A itself, since it appears before the exponential term.
(E) Order factor — Incorrect. The order of a reaction comes from the rate law, not from the Arrhenius equation.
NCERT (2026-27 edition):
Temperature Dependence of the Rate of a Reaction – …
