Learn

Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceOtherMediumMulti-step

JEE Main 7 April 2025, Shift 1, Chemistry Q56

Question 56 of 75 in this shift, Chemistry question 6 of 25, Section A.

Reaction 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 t/mm Hg 10 | 160 ∞\infty | 240 Which of the following option is incorrect?

The figure, in words

Table of total pressure of the system versus time: 160 mm Hg at t = 10 min and 240 mm Hg at t = infinity.
  1. (1)Initial pressure of A is 80 mm Hg
  2. (2)Partial pressure of A after 10 minute is 40 mm Hg
  3. (3)Rate constant of the reaction is 1.693 min−11.693\ \mathrm{min^{-1}}Official answer
  4. (4)The reaction never goes to completion

Official answer

Option 3

NTA final key.

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

Same idea in other shifts

Asked 4× 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. 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
  3. 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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.