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Saturday, 31 October

JEE Main 2021 · ChemistryNumerical answerNumerical valueHardMulti-step

JEE Main 4 August 2021, Shift 2, Chemistry Q59

Question 59 of 90 in this shift, Chemistry question 29 of 30, Section B.

N2O5\mathrm{N_2O_5} decomposes following first order kinetics according to the reaction 2N2O5(g)→4NO2(g)+O2(g)2\mathrm{N_2O_5(g)} \rightarrow 4\mathrm{NO_2(g)} + \mathrm{O_2(g)} N2O5\mathrm{N_2O_5} is introduced in a closed vessel. After 46 minutes, the pressure in the vessel is 549.43 mm of Hg. After a very long time, the pressure saturated at 584.5 mm of Hg. The rate constant of the reaction in hr−1\mathrm{hr^{-1}} is ________ . (Nearest integer) [Assume : ln 10 = 2.3, Assume all gases behave as ideal gases]

Official answer

3

NTA final key.

Chapter
Chemical Kinetics
Topic
Integrated Rate Equations
Idea tested
Gas Kinetics with Complex Stoichiometry

Same idea in other shifts

Asked 6× in all
  1. 2 Apr 2026, Shift 2 · Q72Consider the following gas phase reaction being carried out in a closed vessel at 25°C. 2A(g)⟶4B(g)+C(g)2A(g) \longrightarrow 4B(g) + C(g) | time (min)…MediumNumerical value
  2. 7 Apr 2025, Shift 1 · Q56Reaction A(g)→2B(g)+C(g)\mathrm{A(g) \rightarrow 2B(g) + C(g)} is a first order reaction. It was started with pure A t/min | Pressure of system at time…MediumOtherHas a figure
  3. 1 Feb 2024, Shift 2 · Q86The following data were obtained during the first order thermal decomposition of a gas A at constant volume :…MediumNumerical value
  4. 31 Jan 2024, Shift 1 · Q65Integrated rate law equation for a first order gas phase reaction is given by (where Pi\mathrm{P_i} is initial pressure and Pt\mathrm{P_t}…MediumSingle correct
  5. 13 Apr 2023, Shift 2 · Q87A(g)→2B(g)+C(g)\mathrm{A(g)\rightarrow 2B(g)+C(g)} is a first order reaction. The initial pressure of the system was found to be 800 mm Hg which…MediumNumerical value

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.