JEE Main 2026 · ChemistryMultiple choiceSingle correctEasyConceptual

JEE Main 4 April 2026, Shift 1, Chemistry Q57

Question 57 of 75 in this shift, Chemistry question 7 of 25, Section A.

Consider the first order reaction

\mathrm{R}\rightarrow\mathrm{P}

. The fraction of molecules decomposed in the given first order reaction can be expressed as

(1) $1-e^{k_1t}$
(2) $1+e^{k_1t}$
(3) $1+e^{-k_1t}$
(4) $1-e^{-k_1t}$ Official answer

Official answer

Option 4

NTA final key.

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

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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.