where, A= pre-exponential constant i.e. frequency factor Ea= activation energy R‌‌=‌ gas constant ‌=2kcalmol−1 Tk‌‌=‌ temperature ‌ k‌‌=‌ rate constant ‌ Thus, ‌
Ea
RT
=‌
12000
T
or Ea=12000×R ∴Ea=‌
12000×2
1000
‌‌( in kcalmol−1) i.e. ‌‌Ea=24kcalmol−1 Hence, option (a) is the correct answer.