PYQ Vault
EbooksTutor

Equilibrium

JEE Mains Chemistry. Try each one first, then open its answer.

Top 10 JEE Mains PYQs to practise first

The questions and kinds of question asked most often come first. Each one says how often and in which papers.

  1. Question 1

    This type asked 7 times: 14 Jun 2022, 31 Jan 2024, 23 Jan 2025, 29 Jan 2025, 2 Apr 2025, 23 Jan 2026 S1, 5 Apr 2026 S2. This one: 5 Apr 2026 S2 See all 7 of this type

    31
    The reaction A(g)⇌B(g)+C(g)A(g) \rightleftharpoons B(g) + C(g) was initiated with the amount ' a ' of A(g)A(g). At equilibrium it is found that the amount of A(g)A(g) remaining is (a−x)(a - x) at a total pressure of p. The equilibrium constant KpK_{p} of the reaction can be calculated from the expression :

    Tap an option to check your answer.

  2. Question 2

    This type asked 6 times: 26 Jul 2022, 29 Jan 2023, 4 Apr 2024, 8 Apr 2024, 4 Apr 2026 S1, 8 Apr 2026 S2. This one: 8 Apr 2026 S2 See all 6 of this type

    30
    Consider the following reactions in which all the reactants and products are present in gaseous state 2xy⇌x2+y2 K1=2.5×1052xy \rightleftharpoons x_{2}+y_{2}{\text{ }K}_{1}= 2.5 \times10^{5}
    xy+12z2⇌xyz K2=5×10−3xy +\frac{1}{2}z_{2}\rightleftharpoons xyz\ K_{2}= 5 \times10^{- 3}
    The value of K3K_{3} for the equilibrium 12x2+12y2+12z2⇌xyz\frac{1}{2}x_{2}+\frac{1}{2}y_{2}+\frac{1}{2}z_{2}\rightleftharpoons xyz is :

    Tap an option to check your answer.

  3. Question 3

    This type asked 6 times: 26 Jun 2022, 25 Jan 2023, 13 Apr 2023, 7 Apr 2025, 4 Apr 2026 S1, 4 Apr 2026 S2. This one: 4 Apr 2026 S2 See all 6 of this type

    30
    20 mL of a solution of acetic acid required 28.4 mL of 0.1 M NaOH for its neutralization. A solution (X) was prepared by mixing 20 mL of the above acetic acid and 14.2 mL of 0.1 M NaOH solution. What is the pH of the solution (X) ? (pKa\left( pK_{a} \right. value of acetic acid is 4.75).

    Tap an option to check your answer.

  4. Question 4

    This type asked 6 times: 28 Jun 2022, 26 Jul 2022, 24 Jan 2023, 30 Jan 2024, 22 Jan 2026 S2, 28 Jan 2026 S1. This one: 28 Jan 2026 S1 See all 6 of this type

    31
    Consider a weak base ' B ' of pKb=5.699pK_{b}= 5.699. ' x ' mL of 0.02 M HCl and ' y ' mL of 0.02 M weak base ' B ' are mixed to make 100 mL of a buffer of pH 9 at 25∘C25^{\circ}C. The values of ' xx ' and ' yy ' respectively are: [Given: log⁡2=0.3010,log⁡3=0.4771,log⁡5=0.699\log2 = 0.3010,\log3 = 0.4771,\log5 = 0.699 ]

    Tap an option to check your answer.

  5. Question 5

    This type asked 5 times: 2021 Paper 22, 1 Feb 2024, 22 Jan 2025, 2 Apr 2026 S1, 5 Apr 2026 S1. This one: 5 Apr 2026 S1 See all 5 of this type

    30
    M3 A2M_{3}{\text{ }A}_{2} is a sparingly soluble salt of molar mass y gmol−1gmol^{- 1} and solubility x gL−1x\ gL^{- 1}. The ratio of the molar concentration of the anion ( A3−A^{3 -} ) to the solubility product of the salt is

    Tap an option to check your answer.

  6. Question 6

    This type asked 5 times: 2021 Paper 13, 31 Jan 2023, 29 Jan 2024, 6 Apr 2024, 23 Jan 2026 S1. This one: 23 Jan 2026 S1 See all 5 of this type

    45
    Consider the general reaction given below at 400 K
    xA(g)⇌yB(g)xA(g) \rightleftharpoons yB(g)
    The values of KpK_{p} and KcK_{c} are studied under the same condition of temperature but variation in x and y . (I) Kp=85.87K_{p}= 85.87 and Kc=2.586K_{c}= 2.586 appropriate units (II) Kp=0.862K_{p}= 0.862 and Kc=28.62K_{c}= 28.62 appropriate units The value of xx and yy in (I) and (II) respectively are:

    Tap an option to check your answer.

  7. Question 7

    This type asked 4 times: 2021 Paper 23, 29 Jul 2022, 30 Jan 2023, 5 Apr 2026 S1. This one: 5 Apr 2026 S1 See all 4 of this type

    31
    Arrange the following resultant mixtures in increasing order of their pH values (A) 10 mL0.2MCa(OH)2+25 mL0.1MHCl10\text{ }mL0.2MCa(OH)_{2} + 25\text{ }mL0.1MHCl (B) 10 mL0.01MH2SO4+10 mL0.01MCa(OH)210\text{ }mL0.01MH_{2}{SO}_{4} + 10\text{ }mL0.01MCa(OH)_{2} (C) 10 mL0.1MH2SO4+10 mL0.1MKOH10\text{ }mL0.1MH_{2}{SO}_{4} + 10\text{ }mL0.1MKOH Choose the correct answer from the options given below :

    Tap an option to check your answer.

  8. Question 8

    This type asked 4 times: 28 Jul 2022, 23 Jan 2025, 28 Jan 2026 S1, 2 Apr 2026 S2. This one: 2 Apr 2026 S2 See all 4 of this type

    31
    At 25∘C,20.0 mL25^{\circ}C,20.0\text{ }mL of 0.2 M weak monoprotic acid HX is titrated against 0.2 M NaOH . The pH of the solution (a) at the start of the titration (when NaOH has not been added) and (b) when 10 mL of NaOH is added respectively, are : Given : Ka=5×10−4,pKa=3.3,α≪1K_{a}= 5 \times10^{- 4},pK_{a}= 3.3,\alpha\ll 1

    Tap an option to check your answer.

  9. Question 9

    This type asked 4 times: 6 Apr 2023, 23 Jan 2026 S2, 24 Jan 2026 S2, 28 Jan 2026 S2. This one: 28 Jan 2026 S2 See all 4 of this type

    29
    Observe the following equilibrium in a 1 L flask.
    A(g)⇌B(g)A(g) \rightleftharpoons B(g)
    At T(K)T(K), the equilibrium concentrations of A and B are 0.5 M and 0.375 M respectively. 0.1 moles of A are added into the flask and heated to T(K)T(K) to establish the equilibrium again. The new equilibrium concentrations (in MM ) of AA and BB are respectively.

    Tap an option to check your answer.

  10. Question 10

    This type asked 4 times: 2021 Paper 15, 27 Jun 2022, 29 Jan 2023, 4 Apr 2025. This one: 4 Apr 2025 See all 4 of this type

    125
    x mgx\ mg of Mg(OH)2Mg(OH)_{2} (molar mass =58= 58 ) is required to be dissolved in 1.0 L of water to produce a pH of 10.0 at 298 K . The value of xx is ____\_\_\_\_ mg. (Nearest integer) (Given : Mg(OH)2Mg(OH)_{2} is assumed to dissociate completely in H2OH_{2}O )