JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 26 February 2021, Shift 2, Chemistry Q58

Question 58 of 90 in this shift, Chemistry question 28 of 30, Section B.

If the activation energy of a reaction is 80.9 kJ

\mathrm{mol^{-1}}

, the fraction of molecules at 700 K, having enough energy to react to form products is

e^{-x}

. The value of

x

is __________. (Rounded off to the nearest integer) [Use R

= 8.31

\mathrm{K^{-1}}

\mathrm{mol^{-1}}

]

Official answer

NTA final key.

Chapter: Chemical Kinetics
Topic: Arrhenius Equation
Idea tested: Arrhenius Exponential Form

Same idea in other shifts

Asked 4× in all

6 Apr 2026, Shift 2 · Q75Decomposition of a hydrocarbon follows the equation $k=(5.5\times10^{11}\,\mathrm{s^{-1}})\,e^{\frac{-28000\,\mathrm{K}}{T}}$ . The…EasyNumerical value
30 Jun 2022, Shift 1 · Q84For the reaction P $\rightarrow$ B, the values of frequency factor A and activation energy $\mathrm{E_A}$ are $4\times10^{13}$ s $^{-1}$ …MediumNumerical value
2 Apr 2017 (offline) · Q39Two reactions $R_1$ and $R_2$ have identical pre-exponential factors. Activation energy of $R_1$ exceeds that of $R_2$ by 10 kJ…EasySingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.