1
JEE Main 2026 (Online) 28th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Observe the following equilibrium in a 1 L flask.

A(g) ⇌ B(g)

At T(K), the equilibrium concentrations of A and B are 0.5 M and 0.375 M respectively. 0.1 moles of A is added into the flask and heated to T(K) to establish the equilibrium again. The new equilibrium concentrations (in M) of A and B are respectively

A

0.742, 0.557.

B

0.367, 0.275.

C

0.53, 0.4.

D

0.557, 0.418.

2
JEE Main 2026 (Online) 24th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

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 $\mathrm{P}_2, \mathrm{Q}_2$ and PQ at the new equilibrium, respectively, are

A

$2.56,1.62,2.24$

B

$2.67,2.67,2.67$

C

1.21, 2.24, 1.56

D

$1.66,1.66,1.66$

3
JEE Main 2026 (Online) 23rd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Consider the general reaction given below at 400 K

$$ x \mathrm{~A}(\mathrm{~g}) \rightleftharpoons y \mathrm{~B}(\mathrm{~g}) . $$

The values of $K_p$ and $K_c$ are studied under the same condition of temperature but variation in $x$ and $y$.

(i) $\mathrm{K}_{\mathrm{p}}=85.87$ and $\mathrm{K}_{\mathrm{c}}=2.586$ appropriate units

(ii) $\mathrm{K}_{\mathrm{p}}=0.862$ and $\mathrm{K}_{\mathrm{c}}=28.62$ appropriate units

The values of $x$ and $y$ in (i) and (ii) respectively are :

A
(i) (ii)
1,2 2,1
B
(i) (ii)
1,3 2,1
C
(i) (ii)
3,1 3,1
D
(i) (ii)
4,1 4,1
4
JEE Main 2025 (Online) 3rd April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
In the following system, $\mathrm{PCl}_5(\mathrm{~g}) \leftrightharpoons \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})$ at equilibrium, upon addition of xenon gas at constant T \& p , the concentration of
A
$\mathrm{PCl}_5, \mathrm{PCl}_3 \& \mathrm{Cl}_2$ remain constant
B
$\mathrm{PCl}_3$ will increase
C
$\mathrm{Cl}_2$ will decrease
D
$\mathrm{PCl}_5$ will increase

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