JEE Main 2026 — Chemical Equilibrium Question with Solution
JEE Main 2026 (28 January Shift 2)
Question
Observe the following equilibrium in a 1 L flask.
At , 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 to establish the equilibrium again. The new equilibrium concentrations (in M) of A and B are respectively
At , 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 to establish the equilibrium again. The new equilibrium concentrations (in M) of A and B are respectively
Choose an option
Show full solutionCorrect option: C
Correct answer
C.
Step-by-step explanation
Initial equilibrium:
[A]=0.5 M, [B]=0.375 M;
After adding 0.1 mol A: [A]=0.6 M, [B]=0.375 M; Q=0.625
Q < Kc, so equilibrium shifts right.
Let x be A that decomposes:
0.375+x=0.45-0.75x
1.75x=0.075; x≈0.0429
New [A]=0.6-0.0429=0.557 M; [B]=0.375+0.0429=0.418 M
[A]=0.5 M, [B]=0.375 M;
After adding 0.1 mol A: [A]=0.6 M, [B]=0.375 M; Q=0.625
Q < Kc, so equilibrium shifts right.
Let x be A that decomposes:
0.375+x=0.45-0.75x
1.75x=0.075; x≈0.0429
New [A]=0.6-0.0429=0.557 M; [B]=0.375+0.0429=0.418 M
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This is a previous-year question from JEE Main 2026, covering the Chemical Equilibrium chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.