JEE Main 2020 · ChemistryMultiple choiceSingle correctMediumCalculation

JEE Main 5 September 2020, Shift 1, Chemistry Q44

Question 44 of 75 in this shift, Chemistry question 19 of 25.

A flask contains a mixture of compounds A and B. Both compounds decompose by first-order kinetics. The half-lives for A and B are 300 s and 180 s, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is : (Use

\ln 2 = 0.693

)

(1)300
(2)120
(3)900Official answer
(4)180

Official answer

Option 3

NTA final key (Sep 2020).

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

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Asked 13× 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 108 of the 174 JEE Main shifts held from 2017 to 2026.