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Chemistry - Chemical Equilibrium

Practise 125 JEE Main previous year questions on Chemical Equilibrium, compiled from papers spanning 2002 to 2026. Each question is pulled directly from the actual exam paper it appeared in, so you're practising in the exact style and difficulty JEE Main tests.

Chemical Equilibrium has been asked in 23 of the 25 years of JEE Main papers analysed (2002–2026), with 125 questions in all. 26% of them were easy, 53% moderate and 22% tough. Most of its questions came from 2021, with 15 questions that year. In the last three years (2024–2026) it had 27 questions across 49 papers, about 0.6 per paper.

The chapter's 2 topics are not weighted equally: Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application (106 questions, 85%) and Le chatelier's principle (19 questions, 15%) have been asked the most. Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application has also led over the last five years, with 45 questions. Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application has produced the most tough questions (25).

  1. 1Consider the following reactions in which all the reactants and products are present in gaseous state The value of for the equilibrium is:08 Apr, 2026 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  2. 2Solid carbon, CaO and CaCO are mixed and allowed to attain equilibrium at T K. atm atm The partial pressure of CO is ________ atm08 Apr, 2026 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  3. 3One mole each of He and are taken in a L closed flask and heated to K to establish the following equilibrium. . for this reaction at K is . 06 Apr, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  4. 4In a closed flask at K, one mole of X Y (g) attains equilibrium as given below : At equilibrium, X Y (g) was dissociated and the total press06 Apr, 2026 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  5. 5The values of pressure equilibrium constant recorded at different temperatures for the following equilibrium reaction have been given below 05 Apr, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  6. 6The reaction was initiated with the amount ' ' of . At equilibrium it is found that the amount of remaining is at a total pressure of . The 05 Apr, 2026 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  7. 7At , the equilibrium constant of is . What is the equilibrium constant for at the same temperature?04 Apr, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  8. 8For the following reaction at C and at atm pressure, is dissociated. The magnitude of standard free energy change at this temperature is . _04 Apr, 2026 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  9. 9Observe 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 mol28 Jan, 2026 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  10. 10Consider the following gaseous equilibrium in a closed container of volume ' V ' at . 2 moles each of and are present at equilibrium. Now on24 Jan, 2026 (E)Le chatelier's principle
  11. 11Consider the general reaction given below at 400 K The values of and are studied under the same condition of temperature but variation in an23 Jan, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  12. 12For the following gas phase equilibrium reaction at constant temperature, if the total pressure is and the pressure equilibrium constant is 23 Jan, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  13. 13and are added to a 1 L flask and it is found that the system attains the above equilibrium at with the number of moles of and being 3,3 and 23 Jan, 2026 (E)Le chatelier's principle
  14. 14Dissociation of a gas takes place according to the following chemical reaction. At equilibrium, the total pressure is 1 bar at 300 K. The st22 Jan, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  15. 15For the reaction, , graph is plotted as shown below. Identify correct statements. A. Standard free energy change for the reaction is . B. As21 Jan, 2026 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  16. 16Given below are two statements Statement I : A catalyst cannot alter the equilibrium constant of the reaction, temperature remaining constan03 Apr, 2025 (M)Le chatelier's principle
  17. 17In the following system, at equilibrium, upon addition of xenon gas at constant , the concentration of03 Apr, 2025 (M)Le chatelier's principle
  18. 18Consider the following equilibrium, \( {CO}( {g})+2 {H}_2( {g}) {CH}_3 {OH}( {g})\) 0.1 mol of CO along with a catalyst is present in a \(2 02 Apr, 2025 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  19. 19Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : If being the total pressure, is the pressu02 Apr, 2025 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  20. 20At temperature T, compound \( {AB}_{2( {~g})}\) dissociates as \( {AB}_{2( {~g})} {AB}_{( {g})}+ {1}{2} {~B}_{2( {~g})}\) having degree of d29 Jan, 2025 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  21. 21Consider the equilibrium If the pressure applied over the system increases by two fold at constant temperature then (A) Concentration of rea29 Jan, 2025 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  22. 22was taken in a 1 L reaction vessel and allowed to undergo the following reaction at 500 K The total pressure at equilibrium was found to be 24 Jan, 2025 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  23. 23For the reaction, Attainment of equillibrium is predicted correctly by :24 Jan, 2025 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  24. 24Consider the reaction The equation representing correct relationship between the degree of dissociation (x) of with its equilibrium constant23 Jan, 2025 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  25. 25A vessel at 1000 K contains with a pressure of 0.5 atm . Some of is converted into CO on addition of graphite. If total pressure at equilibr22 Jan, 2025 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  26. 26For the given hypothetical reactions, the equilibrium constants are as follows : \( {aligned} & {X} {Y} ; {K}_1=1.0 \\ & {Y} {Z} ; {K}_2=2.008 Apr, 2024 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  27. 27The equilibrium \( {Cr}_2 {O}_7^{2-} 2 {CrO}_4^{2-}\) is shifted to the right in :08 Apr, 2024 (E)Le chatelier's principle
  28. 28At \(-20^{ } {C}\) and \(1 {~atm}\) pressure, a cylinder is filled with equal number of \( {H}_2, {I}_2\) and \( {HI}\) molecules for the re06 Apr, 2024 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  29. 29The ratio \( {K_P}{K_C}\) for the reaction : \( {CO}_{( {g})}+ {1}{2} {O}_{2( {~g})} {CO}_{2( {~g})}\) is :06 Apr, 2024 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  30. 30The following reaction occurs in the Blast furnance where iron ore is reduced to iron metal \( {Fe}_2 {O}_{3( {~s})}+3 {CO}_{( {g})} {Fe}_{(05 Apr, 2024 (M)Le chatelier's principle
  31. 31The equilibrium constant for the reaction \( {SO}_3( {g}) {SO}_2( {~g})+ {1}{2} {O}_2( {~g})\) is \( {K}_{ {c}}=4.9 10^{-2}\). The value of 04 Apr, 2024 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  32. 32For the given reaction, choose the correct expression of K C from the following: Fe 3 + aq + SCN - aq ⇌ ( FeSCN ) 2 + aq31 Jan, 2024 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  33. 33A g ⇌ B g + C 2 g . The correct relationship between K P , α and equilibrium pressure P is31 Jan, 2024 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  34. 34For the reaction N 2 O 4 ( g ) ⇌ 2 NO 2 ( g ) , K p = 0 . 492 atm at 300 K . K c for the reaction at same temperature is _ _ _ _ _ _ × 10 - 29 Jan, 2024 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  35. 35The following concentrations were observed at 500 K for the formation of NH 3 from N 2 and H 2 . At equilibrium : N 2 = 2 × 10 - 2 M , H 2 =29 Jan, 2024 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  36. 36A mixture of one mole of H 2 O and 1 mole of CO is taken in a 10 litre container and heated to 725 K . At equilibrium 40 % of water by mass 11 Apr, 2023 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  37. 374 . 5 moles each of hydrogen and iodine is heated in a sealed ten litre vessel.At equilibrium, 3 moles of HI were found. The equilibrium con11 Apr, 2023 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  38. 38The number of correct statement/s involving equilibria in physical processes from the following is ________ (A) Equilibrium is possible only10 Apr, 2023 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  39. 39For a concentrated solution of a weak electrolyte ( K eq = equilibrium constant) A 2 B 3 of concentration C , the degree of dissociation is06 Apr, 2023 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  40. 40The equilibrium composition for the reaction PCl 3 + Cl 2 PCl 5 at 298 K is given below: PCl 3 eq = 0 . 2 mol L - 1 , Cl 2 eq = 0 . 1 mol L 06 Apr, 2023 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  41. 41(i) X ( g ) Y ( g ) + Z ( g ) K p 1 = 3 (ii) A ( g ) 2 B ( g ) K p 2 = 1 If the degree of dissociation and initial concentration of both the01 Feb, 2023 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  42. 42The effect of addition of helium gas to the following reaction in equilibrium state at constant volume, is : PCI 5 ( g ) PCl 3 ( g ) + Cl 2 01 Feb, 2023 (E)Le chatelier's principle
  43. 43For reaction: SO 2 ( g ) + 1 2 O 2 ( g ) SO 3 ( g ) K P = 2 10 12 at 27 C and 1 atm pressure. The K c for the same reaction is 10 13 . ( Nea31 Jan, 2023 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  44. 44Consider the following equation: 2 SO 2 g + O 2 g 2 SO 3 g , H = - 190 kJ . The number of factors which will increase the yield of SO 3 at e30 Jan, 2023 (E)Le chatelier's principle
  45. 45Water decomposes at 2300 K H 2 O g H 2 g + 1 2 O 2 g The percent of water decomposing at 2300 K and 1 bar is _____ (Nearest integer). Equili29 Jan, 2023 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  46. 46At 298 K N 2 g + 3 H 2 g 2 NH 3 g , K 1 = 4 10 5 N 2 g + O 2 g 2 NO g , K 2 = 1 . 6 10 12 H 2 g + 1 2 O 2 g H 2 O ( g ) , K 3 = 1 . 0 10 - 129 Jan, 2023 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  47. 47At 600 K , 2 mol of NO are mixed with 1 mol of O 2 . 2 NO g + O 2 g 2 NO 2 g The reaction occurring as above comes to equilibrium under a to28 Jul, 2022 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  48. 48At 298 K , the equilibrium constant is 2 10 15 for the reaction: Cu s + 2 Ag + aq Cu 2 + aq + 2 Ag s The equilibrium constant for the reacti26 Jul, 2022 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  49. 494 . 0 moles of argon and 5 . 0 moles of PCl 5 are introduced into an evacuated flask of 100 litre capacity at 610 K . The system is allowed 29 Jun, 2022 (E)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application
  50. 502 NOCl g 2 NO g + Cl 2 g In an experiment, 2 . 0 moles of NOCl was placed in a one-litre flask and the concentration of NO after equilibrium27 Jun, 2022 (M)Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application

Frequently Asked Questions

1.How many questions are available for Chemical Equilibrium?

This chapter includes 125 questions compiled from JEE Main papers spanning 2002 to 2026.

2.Are these questions only from JEE Main, or from other exams too?

These are JEE Main questions specifically for the Chemical Equilibrium chapter. Questions from other exams like NTA Abhyas (JEE Main) or JEE Advanced are organised separately under their respective exam sections.

3.Is Chemical Equilibrium an important chapter for JEE Main Chemistry?

Chemical Equilibrium has appeared in 23 of the 25 years of JEE Main papers covered here, with 125 questions across 107 papers - about one per paper it appears in.

4.What is the difficulty level of Chemical Equilibrium questions in JEE Main?

Of the 125 questions analysed for this chapter, 26% are easy, 53% moderate and 22% tough. 2021 had the most, with 15 questions.

5.Which topics in Chemical Equilibrium should I focus on?

These topics have carried the most weightage in Chemical Equilibrium:

  • Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application - 106 questions (85%)
  • Le chatelier's principle - 19 questions (15%)
  • Law of Mass Action, Equilibrium Constant (Kc and Kp) and its Application has produced the most tough questions (25).
6.Is Chemical Equilibrium's weightage in JEE Main going up or down?

Across all 107 papers analysed, Chemical Equilibrium has averaged about 1.2 questions per paper. In the last three years (2024–2026), that average has fallen, at about 0.6 questions per paper. Use the year-wise numbers on this page for the exact trend before you decide how much time to give it.