Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : A ( g ) rightleftharpoons B ( g )+ C ( g ) If p being the total pressure, K p is the pressure equilibrium constant and α is the degree of dissociation, then which of the following is true at equilibrium?

If K p value is extremely high compared to p, α becomes much less than unity

If p value is extremely high compared to K p , α approx 1

Chemistry · Chemical Equilibrium

JEE Main 2025 — 2 April, Evening Shift — Question 17

Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : $\mathrm{A}(\mathrm{g}) \rightleftharpoons \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$ If $p$ being the total pressure, $K_{p}$ is the pressure equilibrium constant and $\alpha$ is the degree of dissociation, then which of the following is true at equilibrium?

Option A:
If $K_{p}$ value is extremely high compared to $p, \alpha$ becomes much less than unity
Option B:
When $p$ increases $\alpha$ increases
Option C:
If $p$ value is extremely high compared to $K_{p}, \alpha \approx 1$
Option D:
When $p$ increases $\alpha$ decreases
Correct

Answer: D

Step-by-step solution

According to Le-Chatelier's principle as pressure increases in above reaction the reaction moves in backward

direction hence $\alpha$ decreases.

Answer key and solution verified before publishing.

Practise Chemical Equilibrium

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Solve a similar one free

Exam: JEE Main 2025
Paper: 2 April, Evening Shift
Subject: Chemistry
Chapter: Chemical Equilibrium
Topic: Factors affecting equilibrium &Le Chatelier's Principle