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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctEasyCalculation

JEE Main 8 April 2025, Shift 2, Chemistry Q54

Question 54 of 75 in this shift, Chemistry question 4 of 25, Section A.

In a first order decomposition reaction, the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are t1t_1 and t2t_2 (s), respectively. The ratio t1/t2t_1/t_2 will be:
  1. (1)43\frac{4}{3}
  2. (2)32\frac{3}{2}
  3. (3)34\frac{3}{4}
  4. (4)23\frac{2}{3}Official answer

Official answer

Option 4

NTA final key.

Chapter
Chemical Kinetics
Topic
Integrated Rate Equations
Idea tested
Concentration After n Half-Lives

Same idea in other shifts

Asked 3× in all
  1. 6 Apr 2026, Shift 1 · Q74Sucrose hydrolyses in acidic medium into glucose and fructose by first order rate law with t1/2=3\mathrm{t_{1/2}}=3 hour. The percentage of…EasyNumerical value
  2. 3 Apr 2025, Shift 1 · Q58In a reaction A+B→C\mathrm{A} + \mathrm{B} \rightarrow \mathrm{C}, initial concentrations of A and B are related as…MediumSingle correct

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.