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NEET Equilibrium: 5 practice MCQs with answers

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

Equilibrium combines chemical equilibrium and ionic equilibrium, and it gives some of the most calculation-heavy questions in Class 11 Chemistry. The five MCQs below test the relation between Kp and Kc, pH of a strong base, Le Chatelier's principle, an equilibrium constant calculation and the pH of a buffer.

What this chapter covers in the NEET syllabus

Equilibrium is an NMC Chemistry unit, matching the NCERT Class 11 chapter. The topics are:

• Equilibrium in physical and chemical processes, and its dynamic nature.
• The law of mass action, the equilibrium constants Kc and Kp, and the reaction quotient.
• Factors affecting equilibrium and Le Chatelier's principle.
• Ionic equilibrium: strong and weak electrolytes, degree of ionisation and acid and base strength.
• pH, the ionic product of water, hydrolysis of salts and buffer solutions with the Henderson equation.
• Solubility product and the common ion effect.

Five practice MCQs on Equilibrium

Question 1

For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the relation between Kp and Kc is:

• A. Kp = Kc (RT)⁻²
• B. Kp = Kc (RT)²
• C. Kp = Kc
• D. Kp = Kc (RT)⁻¹

Question 2

The pH of a 0.01 M NaOH solution at 298 K is:

• A. 2
• B. 10
• C. 12
• D. 13

Question 3

The formation of ammonia, N₂ + 3H₂ ⇌ 2NH₃, is exothermic. According to Le Chatelier's principle, the yield of NH₃ is favoured by:

• A. high temperature and low pressure
• B. low temperature and high pressure
• C. high temperature and high pressure
• D. low temperature and low pressure

Question 4

For N₂O₄ ⇌ 2NO₂, the equilibrium concentrations are [N₂O₄] = 0.1 M and [NO₂] = 0.2 M. The value of Kc is:

• A. 0.04
• B. 0.2
• C. 4
• D. 0.4

Question 5

A buffer contains 0.1 M acetic acid and 0.1 M sodium acetate. If pKa of acetic acid is 4.76, the pH of the buffer is:

• A. 2.38
• B. 4.76
• C. 7.00
• D. 9.24

Answers and explanations

1. A. Kp = Kc (RT)^Δn, where Δn is the change in moles of gas. Here Δn = 2 − (1 + 3) = −2, so Kp = Kc (RT)⁻². If Δn = 0, Kp equals Kc.
2. C. NaOH is a strong base, so [OH⁻] = 0.01 M and pOH = 2. At 298 K, pH + pOH = 14, so pH = 12. A common slip is to quote pOH as the pH.
3. B. The forward reaction releases heat, so lowering the temperature shifts the equilibrium to the right. The forward reaction also reduces the moles of gas from 4 to 2, so higher pressure favours NH₃. (Industry uses a compromise temperature to keep the rate acceptable.)
4. D. Kc = [NO₂]²/[N₂O₄] = (0.2)²/0.1 = 0.04/0.1 = 0.4. Option A forgets to divide by [N₂O₄].
5. B. By the Henderson equation, pH = pKa + log([salt]/[acid]) = 4.76 + log(0.1/0.1) = 4.76 + 0 = 4.76. When acid and salt concentrations are equal, pH = pKa.

How to prepare Equilibrium

• Write Kc from the balanced equation, every time. Products over reactants, each raised to its coefficient. Leave out pure solids and liquids. If the equation is reversed, K becomes 1/K, and if it is multiplied by n, K is raised to the power n.
• Compare Q with K to predict direction. If Q is less than K, the reaction proceeds forward, and if Q is more than K, it goes backward. This is the tool behind every Le Chatelier question.
• Learn what changes K and what does not. Only temperature changes the value of K. A change in concentration, pressure or a catalyst can shift the position of equilibrium or its speed, but not the constant.
• Practise ICE tables (initial, change, equilibrium) for degree-of-dissociation problems. Set up x, substitute into K, and use the approximation x much smaller than the initial value only when the check works.
• Know the ionic equilibrium formulas. pH = −log[H⁺]; for a weak acid [H⁺] = √(Ka C); Ksp for AB is s² and for AB₂ is 4s³; buffer pH = pKa + log(salt/acid); and the pH range of a salt solution from hydrolysis.

Equilibrium is calculation-heavy, so schedule 20 numericals across two sessions and revise formulas weekly. See the NEET Chemistry preparation guide for planning and the NEET syllabus for all units.

Take a full Equilibrium test on PrepMatic

Equilibrium rewards practice with calculations, and PrepMatic's results show your accuracy and speed per question, which tells you whether the slow part is the setup or the arithmetic. A topic test is about 15 questions in 30 minutes. The free Basic plan includes topic tests, and more chapters are on the practice hub.

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