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Saturday, 31 October

JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumData or graph

JEE Main 31 August 2021, Shift 1, Chemistry Q53

Question 53 of 90 in this shift, Chemistry question 23 of 30, Section B.

According to the following figure, the magnitude of the enthalpy change of the reaction A+B→M+N\mathrm{A+B\rightarrow M+N} in kJ mol−1^{-1} is equal to __________. (Integer answer)

The figure, in words

Energy (vertical) vs Reaction Coordinate (horizontal) profile: A+B at a higher level on the left, curve rises to a peak then falls to a lower level M+N on the right. Dotted line at the A+B level; arrow x from that dotted level up to the peak; arrow y from the A+B dotted level down to the dotted level of M+N; arrow z from the M+N dotted level down to the horizontal axis. Printed values: x = 20 kJ mol^-1, y = 45 kJ mol^-1, z = 15 kJ mol^-1.

Official answer

45

NTA final key.

Chapter
Chemical Kinetics
Topic
Arrhenius Equation
Idea tested
Reaction Energy Profiles

Same idea in other shifts

Asked 4× in all
  1. 2 Apr 2025, Shift 2 · Q56Reactant A converts to product D through the given mechanism (with the net evolution of heat) : A→BA \rightarrow B slow; ΔH=+\Delta H = +ve…MediumDiagram basedHas a figure
  2. 6 Apr 2023, Shift 2 · Q63Consider the following reaction that goes from A to B in three steps as shown below: Choose the correct option Number of intermediates |…MediumDiagram basedHas a figure
  3. 8 Apr 2023, Shift 2 · Q63The correct reaction profile diagram for a positive catalyst reaction.EasyDiagram basedHas a figure

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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.