JEE Main 2021 · ChemistryNumerical answerNumerical valueEasyCalculation

JEE Main 17 March 2021, Shift 1, Chemistry Q58

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

For a certain first order reaction 32% of the reactant is left after 570 s. The rate constant of this reaction is __________

\times 10^{-3}\ \mathrm{s^{-1}}

. (Round off to the Nearest Integer). [Given :

\log_{10}2 = 0.301

\ln 10 = 2.303

]

Official answer

NTA final key.

Chapter: Chemical Kinetics
Topic: Integrated Rate Equations
Idea tested: First Order Integrated Rate Law

Same idea in other shifts

Asked 13× in all

4 Apr 2026, Shift 2 · Q74For a first order reaction $\mathrm{A\rightarrow B}$ [table: t/min = 0, x, 20; [A]/M = 0.6500, 0.0650, 0.00065] $x=$ ________ min.…MediumNumerical value
5 Apr 2026, Shift 1 · Q75If the half life of a first order reaction is 6.93 minutes then the time required for completion of 99% of the reaction will be ________…EasyNumerical value
2 Apr 2025, Shift 2 · Q71For the reaction $A \rightarrow B$ the following graph was obtained. The time required (in seconds) for the concentration of A to reduce…MediumNumerical valueHas a figure
30 Jan 2024, Shift 1 · Q87The rate of First order reaction is 0.04 mol L $^{-1}$ s $^{-1}$ at 10 minutes and 0.03 mol L $^{-1}$ s $^{-1}$ at 20 minutes after…MediumNumerical value
26 Jul 2022, Shift 2 · Q64At 30°C, the half life for the decomposition of $\mathrm{AB_2}$ is 200 s and is independent of the initial concentration of…MediumSingle correct
3 Aug 2021, Shift 2 · Q57The inactivation process of virus is first order with respect to virus concentration and 2% of the virus was inactivated in the first one…MediumNumerical value
31 Aug 2021, Shift 1 · Q56For a first order reaction, the ratio of the time for 75% completion of a reaction to the time for 50% completion is __________. (Integer…EasyNumerical value
24 Feb 2021, Shift 2 · Q57Sucrose hydrolyses in acid solution into glucose and fructose following first order rate law with a half-life of 3.33 h at $25^\circ$ C.…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.