JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 24 February 2021, Shift 1, Chemistry Q58

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

Gaseous cyclobutene isomerizes to butadiene in a first order process which has a ‘k’ value of

3.3\times10^{-4}\ \mathrm{s^{-1}}

at 153°C. The time in minutes it takes for the isomerization to proceed 40% to completion at this temperature is __________. (Rounded off to the nearest integer)

Official answer

NTA final key.

Chapter: Chemical Kinetics
Topic: Integrated Rate Equations
Idea tested: First Order Fractional Completion Shortcuts

Same idea in other shifts

Asked 6× in all

6 Apr 2024, Shift 1 · Q85Time required for 99.9% completion of a first order reaction is __________ times the time required for completion of 90% reaction.(nearest…EasyNumerical value
8 Apr 2024, Shift 1 · Q85Consider the following reaction $\mathrm{A + B \rightarrow C}$ The time taken for A to become $1/4^{\mathrm{th}}$ of its initial…MediumNumerical value
24 Jun 2022, Shift 2 · Q65For a first order reaction, the time required for completion of 90% reaction is 'x' times the half life of the reaction. The value of 'x'…EasySingle correct
28 Jun 2022, Shift 1 · Q88For a first order reaction A $\rightarrow$ B, the rate constant, k = $5.5 \times 10^{-14}$ $\mathrm{s^{-1}}$ . The time required for 67%…MediumNumerical value
18 Mar 2021, Shift 2 · Q57A reaction has a half life of 1 min. The time required for 99.9% completion of the reaction is __________ min. (Round off to the Nearest…EasyNumerical 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.