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Equilibrium

JEE Main 2025 (Online) 2nd April Evening ShiftMCQMedium📈 Topic in 18% papers+4−1
Ques. 1JEE Main 2025, 2 April (Evening Shift)

Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : A(g) B(g) + C(g) If p is the total pressure, Kp is the pressure equilibrium constant and is the degree of dissociation, then which of the following is true at equilibrium?

  1. If Kp value is extremely high compared to p, becomes much less than unity
  2. When p increases, increases
  3. If p value is extremely high compared to Kp, 1
  4. When p increases, decreases

Answer

(4) When p increases, decreases

Solution

Take 1 mol of A initially.

At equilibrium: A = (1 - ), B = , C = ; total = (1 + ) mol

pA = 1 - 1 + p, pB = pC = 1 + p

Kp = pB pCpA = 2 p(1 + )(1 - ) = 2 p1 - 2

= KpKp + p

(1) Kp p 1, not much less than unity — incorrect.

(2), (4) At constant temperature Kp is constant; as p increases, KpKp + p decreases, so decreases (Le Chatelier: higher pressure favours the side with fewer gas moles, i.e. A). Hence (2) is incorrect and (4) is correct.

(3) p Kp Kpp 1, not 1 — incorrect.

Answer: (4)

Keep practising — Equilibrium

Ques. 2JEE Main 2025, 29 January (Morning Shift)

At temperature T, compound AB2(g) dissociates as AB2(g) AB(g) + 12B2(g) having degree of dissociation x (small compared to unity). The correct expression for x in terms of Kp and p is:

  1. Kp
  2. [3] 2Kp2p
  3. [3] 2Kpp
  4. [4] 2Kpp
Ques. 3JEE Main 2025, 29 January (Evening Shift)

Consider the equilibrium CO(g) + 3H2(g) CH4(g) + H2O(g) If the pressure applied over the system increases by two fold at constant temperature then

  1. (A) and (B) only
  2. (A), (B) and (D) only
  3. (B) and (C) only
  4. (A), (B) and (C) only
Ques. 4JEE Main 2025, 28 January (Morning Shift)

A weak acid HA has degree of dissociation x. Which option gives the correct expression of (pH - pKa)?

  1. ( 1-xx )
  2. 0
  3. (1+2x)
  4. ( x1-x )
Ques. 5JEE Main 2025, 28 January (Morning Shift)

Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K. If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following

  1. Liquid phase disappears completely.
  2. The amount of ice decreases.
  3. The solid phase (ice) disappears completely.
  4. Volume of system increases.
Ques. 6JEE Main 2025, 28 January (Evening Shift)

Arrange the following in increasing order of solubility product : Ca(OH)2, AgBr, PbS, HgS

  1. PbS < HgS < Ca(OH)2 < AgBr
  2. HgS < AgBr < PbS < Ca(OH)2
  3. HgS < PbS < AgBr < Ca(OH)2
  4. Ca(OH)2 < AgBr < HgS < PbS
Ques. 7JEE Main 2025, 24 January (Morning Shift)

Ksp for Cr(OH)3 is 1.6 10-30. What is the molar solubility of this salt in water?

  1. [5]1.8 10-30
  2. 1.8 10-3027
  3. [4] 1.6 10-3027
  4. [2]1.6 10-30
Ques. 8JEE Main 2025, 24 January (Morning Shift)

37.8 g N2O5 was taken in a 1 L reaction vessel and allowed to undergo the following reaction at 500 K 2N2O5(g) 2N2O4(g) + O2(g) The total pressure at equilibrium was found to be 18.65 bar. Then, Kp = 10-2 [nearest integer] Assume N2O5 to behave ideally under these conditions. Given: R = 0.082 bar L mol-1 K-1

Ques. 9JEE Main 2025, 24 January (Evening Shift)

For the reaction, H2(g)+I2(g) 2HI(g) Attainment of equilibrium is predicted correctly by :

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 10JEE Main 2025, 23 January (Morning Shift)

Which of the following happens when NH4OH is added gradually to the solution containing 1 M A2+ and 1M B3+ ions? Given : Ksp [A(OH)2] = 9 10-10 and Ksp [B(OH)3] = 27 10-18 at 298 K.

  1. A(OH)2 will precipitate before B(OH)3
  2. A(OH)2 and B(OH)3 will precipitate together
  3. Both A(OH)2 and B(OH)3 do not show precipitation with NH4OH
  4. B(OH)3 will precipitate before A(OH)2
Ques. 11JEE Main 2025, 23 January (Morning Shift)

If 1 mM solution of ethylamine produces pH=9, then the ionization constant (Kb) of ethylamine is 10-x. The value of x is (nearest integer). [The degree of ionization of ethylamine can be neglected with respect to unity.]

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