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Saturday, 31 October

JEE Main 2026 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 6 April 2026, Shift 1, Chemistry Q57

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

One mole each of He and A(g) are taken in a 10 L closed flask and heated to 400 K to establish the following equilibrium. A(g)⇌B(g)\mathrm{A(g)\rightleftharpoons B(g)} Kc\mathrm{K_c} for this reaction at 400 K is 4.0. The partial pressures (in atm) of He and B(g) are respectively (at equilibrium) (Assume He, A(g) and B(g) behave as ideal gases) (Given : R = 0.082 L atm K−1^{-1} mol−1^{-1})
  1. (1)3.28, 2.624Official answer
  2. (2)2.624, 3.28
  3. (3)3.28, 0.656
  4. (4)0.656, 6.56

Official answer

Option 1

NTA final key.

Chapter
Equilibrium
Topic
Chemical Equilibrium
Idea tested
Dalton's Law in Kp Calculations

Same idea in other shifts

Asked 3× in all
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  2. 10 Apr 2023, Shift 2 · Q85A(g)⇌2B(g)+C(g)\mathrm{A}(g) \rightleftharpoons 2\mathrm{B}(g) + \mathrm{C}(g) For the given reaction, if the initial pressure is 450 mm Hg and the…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.