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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctMediumConceptual

JEE Main 2 April 2025, Shift 2, Chemistry Q55

Question 55 of 75 in this shift, Chemistry question 5 of 25, Section A.

Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : A(g)⇌B(g)+C(g)\mathrm{A(g) \rightleftharpoons B(g) + C(g)} If pp being the total pressure, KpK_p is the pressure equilibrium constant and α\alpha is the degree of dissociation, then which of the following is true at equilibrium ?
  1. (1)When pp increases α\alpha decreasesOfficial answer
  2. (2)When pp increases α\alpha increases
  3. (3)If pp value is extremely high compared to KpK_p, α≈1\alpha \approx 1
  4. (4)If KpK_p value is extremely high compared to pp, α\alpha becomes much less than unity

Official answer

Option 1

NTA final key.

Chapter
Equilibrium
Topic
Chemical Equilibrium
Idea tested
Kp for PCl5 Dissociation Type Reactions

Same idea in other shifts

Asked 3× in all
  1. 5 Apr 2026, Shift 2 · Q56The reaction A(g)⇌B(g)+C(g)\mathrm{A(g)\rightleftharpoons B(g)+C(g)} was initiated with the amount 'a' of A(g). At equilibrium it is found that the…MediumSingle correct
  2. 31 Jan 2024, Shift 2 · Q64A(g)⇌B(g)+C2(g)\mathrm{A_{(g)}\rightleftharpoons B_{(g)}+\frac{C}{2}{}_{(g)}} The correct relationship between Kp\mathrm{K_p}, α\alpha and equilibrium…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.