Chemical Equilibrium JEE Main PYQs PDF, 2020–2026

Chemical Equilibrium questions per year

in the free PDF asked, not in the PDFThe PDF only has questions we can print in full with a checked answer, so it holds 81 of the 85 asked.

Topic-wise weightage by year

How many Chemical Equilibrium questions each topic had in every JEE Main year (all shifts), counting every question asked, including ones not in the PDF. Darker cells mean more questions.

Swipe the table sideways for older years.

Newest questions (2026)

The 12 newest of the 14 JEE Main 2026 Chemical Equilibrium questions in the free PDF, latest shift first.

1. JEE Main 2026 · 8 Apr · Shift 2 · Law of Mass Action

   Solid carbon, CaO and ${\mathrm{CaCO}}_{3}$ are mixed and allowed to attain equilibrium at T K .

   $\begin{array}{cc}{\mathrm{CaCO}}_{3}({\ \mathrm{s}})\rightleftharpoons {\mathrm{CaO}}({\ \mathrm{s}})+{\mathrm{CO}}_{2}({\ \mathrm{g}}) & {\mathrm{Kp}}_{1}=0.08{\ \mathrm{atm}} \\ {\mathrm{C}}({\ \mathrm{s}})+{\mathrm{CO}}_{2}({\ \mathrm{g}})\rightleftharpoons 2{\mathrm{CO}}({\ \mathrm{g}}) & {\mathrm{Kp}}_{2}=2{\ \mathrm{atm}}\end{array}$

   The partial pressure of CO is __ $\times {10}^{{-1}}{\ \mathrm{atm}}$

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2. JEE Main 2026 · 8 Apr · Shift 2 · Law of Mass Action

   Consider the following reactions in which all the reactants and products are present in gaseous state

   $\begin{array}{cc} & 2xy\rightleftharpoons x_{2}+y_{2}\quad {\ \mathrm{K}}_{1}=2.5\times {10}^{5} \\ & xy+\frac{1}{2}z_{2}\rightleftharpoons xyz\quad {\ \mathrm{K}}_{2}=5\times {10}^{{-3}}\end{array}$

   The value of ${\mathrm{K}}_{3}$ for the equilibrium $\frac{1}{2}x_{2}+\frac{1}{2}y_{2}+\frac{1}{2}z_{2}\rightleftharpoons xyz$ is :

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3. JEE Main 2026 · 6 Apr · Shift 1 · Law of Mass Action

   One mole each of He and ${\mathrm{A}}({\mathrm{g}})$ are taken in a 10 L closed flask and heated to 400 K to establish the following equilibrium.

   ${\mathrm{A}}({\ \mathrm{g}})\rightleftharpoons {\mathrm{B}}({\ \mathrm{g}})$

   ${\mathrm{K}}_{{{\mathrm{c}}}}$ for this reaction at 400 K is 4.0 . The partial pressures (in atm) of He and B(g) are respectively (at equilibrium)

   (Assume ${\mathrm{He}},{\mathrm{A}}({\mathrm{g}})$ and ${\mathrm{B}}({\mathrm{g}})$ behave as ideal gases)

   (Given : ${\mathrm{R}}=0.082{\ \mathrm{L}}{\ \mathrm{atm}}{\ \mathrm{K}}^{{-1}}{\ \mathrm{mol}}^{{-1}}$ )

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4. JEE Main 2026 · 6 Apr · Shift 2 · Law of Mass Action

   In a closed flask at 600 K , one mole of ${\mathrm{X}}_{2}{\mathrm{Y}}_{4}({\ \mathrm{g}})$ attains equilibrium as given below :

   ${\mathrm{X}}_{2}{\mathrm{Y}}_{4}({\ \mathrm{g}})\rightleftharpoons 2{\mathrm{XY}}_{2}({\ \mathrm{g}})$

   At equilibrium, $75\%{\mathrm{X}}_{2}{\mathrm{Y}}_{4}({\ \mathrm{g}})$ was dissociated and the total pressure is 1 atm . The magnitude of $\Delta_{{{\mathrm{r}}}}{\mathrm{G}}^{{\ominus}}$ (in ${\mathrm{kJ}}{\mathrm{mol}}^{{-1}}$ ) at this temperature is $\_\_\_\_$ . (Nearest Integer)

   (Given : ${\mathrm{R}}=8.3{\ \mathrm{J}}{\ \mathrm{mol}}^{{-1}}{\ \mathrm{K}}^{{-1}};\ln 10=2.3,\log 2=0.3,\log 3=0.48,\log 5=0.69,\log 7=0.84$ )

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5. JEE Main 2026 · 5 Apr · Shift 1 · Law of Mass Action

   The values of pressure equilibrium constant recorded at different temperatures for the following equilibrium reaction have been given below ${\mathrm{A}}({\mathrm{g}})\rightleftharpoons {\mathrm{B}}({\mathrm{g}})+{\mathrm{C}}({\mathrm{g}})$

   $\begin{array}{cc}\frac{1}{{\ \mathrm{T}}}\left({\ \mathrm{K}}^{{-1}}\right) & \log_{{10}}{\ \mathrm{K}}_{{{\mathrm{p}}}} \\ 0.05 & 3.5 \\ 0.06 & 2.5 \\ 0.07 & 1.5\end{array}$

   The magnitude of $\frac{\Delta{\mathrm{H}}^{{\circ}}}{{\mathrm{R}}}$ calculated from the above data is $\_\_\_\_$ . (Nearest integer)

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6. JEE Main 2026 · 5 Apr · Shift 2 · Law of Mass Action

   The reaction ${\mathrm{A}}({\mathrm{g}})\rightleftharpoons {\mathrm{B}}({\mathrm{g}})+{\mathrm{C}}({\mathrm{g}})$ was initiated with the amount ' a ' of ${\mathrm{A}}({\mathrm{g}})$. At equilibrium it is found that the amount of ${\mathrm{A}}({\mathrm{g}})$ remaining is ( ${\mathrm{a}}-x$ ) at a total pressure of p .

   The equilibrium constant Kp of the reaction can be calculated from the expression :

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7. JEE Main 2026 · 4 Apr · Shift 2 · Law of Mass Action

   For the following reaction at ${50}^{{\circ}}{\mathrm{C}}$ and at 2 atm pressure,

   $2{\ \mathrm{N}}_{2}{\mathrm{O}}_{5}({\ \mathrm{g}})\rightleftharpoons 2{\ \mathrm{N}}_{2}{\mathrm{O}}_{4}({\ \mathrm{g}})+{\mathrm{O}}_{2}({\ \mathrm{g}})$

   ${\mathrm{N}}_{2}{\mathrm{O}}_{5}$ is $50\%$ dissociated.

   The magnitude of standard free energy change at this temperature is $x$.

   $x=$ $\_\_\_\_$ ${\mathrm{J}}{\mathrm{mol}}^{{-1}}$ [Nearest integer].

   Given : ${\mathrm{R}}=8.314{\ \mathrm{J}}{\ \mathrm{mol}}^{{-1}}{\ \mathrm{K}}^{{-1}},\log 2=0.30,\log 3=0.48,\ln 10=2.303$, ${}^{{\circ}}{\mathrm{C}}+273={\mathrm{K}}$

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8. JEE Main 2026 · 4 Apr · Shift 1 · Law of Mass Action

   At ${\mathrm{T}}({\mathrm{K}})$, the equilibrium constant of
   
   ${\mathrm{A}}_{2}(g)+{\mathrm{B}}_{2}(g)\rightleftharpoons {\mathrm{C}}(g)$ is $2.7\times {10}^{{-5}}$.
   
   What is the equilibrium constant for
   
   $\frac{1}{3}{\ \mathrm{A}}_{2}({\ \mathrm{g}})+\frac{1}{3}{\ \mathrm{B}}_{2}({\ \mathrm{g}})\rightleftharpoons \frac{1}{3}{\mathrm{C}}({\mathrm{g}})$ at the same temperature?

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9. JEE Main 2026 · 28 Jan · Shift 2 · Law of Mass Action

   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

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10. JEE Main 2026 · 24 Jan · Shift 2 · Le Chatelier's Principle

    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

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11. JEE Main 2026 · 23 Jan · Shift 1 · Law of Mass Action

    For the following gas phase equilibrium reaction at constant temperature,

    ${\mathrm{NH}}_{3}({\ \mathrm{g}})\rightleftharpoons 1/2{\ \mathrm{N}}_{2}({\ \mathrm{g}})+3/2{\mathrm{H}}_{2}({\ \mathrm{g}})$

    if the total pressure is $\sqrt{3}{\ \mathrm{atm}}$ and the pressure equilibrium constant $(K_{p})$ is 9 atm , then the degree of dissociation is given as $\left(x\times {10}^{{-2}}\right)^{{-1/2}}$. The value of $x$ is $\_\_\_\_$ . (nearest integer)

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12. JEE Main 2026 · 23 Jan · Shift 1 · Law of Mass Action

    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 :

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