JEE Main 2026 — Chemistry Physical Chemistry

2026mcqhard

Consider the following gaseous equilibrium in a closed container of volume ' V ' at $\mathrm{T}(\mathrm{K})$ .

$\mathrm{P}_{2}(\mathrm{~g})+\mathrm{Q}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{PQ}(\mathrm{g})$

2 moles each of $\mathrm{P}_{2}(\mathrm{~g}), \mathrm{Q}_{2}(\mathrm{~g})$ and $\mathrm{PQ}(\mathrm{g})$ are present at equilibrium. Now one mole each of ' $\mathrm{P}_{2}$ ' and ' $\mathrm{Q}_{2}$ ' are added to the equilibrium keeping the temperature at $\mathrm{T}(\mathrm{K})$ . The number of moles of $P_{2}, Q_{2}$ and $P Q$ at the new equilibrium, respectively, are

Official previous-year question

Held on 24 Jan 2026 · Verified 6 Jul 2026.

Options

A
$1.66,1.66,1.66$
B
$2.56,1.62,2.24$
C
$2.67,2.67,2.67$
D
$1.21,2.24,1.56$

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Solution

Initial equilibrium: 2 moles each of $P_2$ , $Q_2$ , $PQ$ with $K = \frac{[PQ]^2}{[P_2][Q_2]} = \frac{4}{4} = 1$ .

After adding 1 mole each of $P_2$ and $Q_2$ : initial composition is $(3, 3, 2)$ . Reaction quotient $Q = \frac{4}{9} < K$ , so reaction shifts right.

Let x moles of reactants combine:

$\frac{(2+2x)^2}{(3-x)^2} = 1$

$2+2x = 3-x$

$3x = 1$ → $x = \frac{1}{3}$

Final moles: $P_2 = 3 - \frac{1}{3} = 2.67$ , $Q_2 = 2.67$ , $PQ = 2 + \frac{2}{3} = 2.67$

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Solution

Initial equilibrium: 2 moles each of $P_2$ , $Q_2$ , $PQ$ with $K = \frac{[PQ]^2}{[P_2][Q_2]} = \frac{4}{4} = 1$ .

After adding 1 mole each of $P_2$ and $Q_2$ : initial composition is $(3, 3, 2)$ . Reaction quotient $Q = \frac{4}{9} < K$ , so reaction shifts right.

Let x moles of reactants combine:

$\frac{(2+2x)^2}{(3-x)^2} = 1$

$2+2x = 3-x$

$3x = 1$ → $x = \frac{1}{3}$

Final moles: $P_2 = 3 - \frac{1}{3} = 2.67$ , $Q_2 = 2.67$ , $PQ = 2 + \frac{2}{3} = 2.67$

JEE Main 2026 — Chemistry Physical Chemistry

Options

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Solution

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JEE Main Physical Chemistry in other years

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JEE Main 2026 — Chemistry Physical Chemistry

Options

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry