JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumMulti-step

JEE Main 16 March 2021, Shift 2, Chemistry Q58

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

A and B decompose via first order kinetics with half-lives 54.0 min and 18.0 min respectively. Starting from an equimolar non reactive mixture of A and B, the time taken for the concentration of A to become 16 times that of B is ________ min. (Round off to the Nearest Integer).

Official answer

108

NTA final key.

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

Same idea in other shifts

Asked 5× in all

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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 42 of the 174 JEE Main shifts held from 2017 to 2026.