Equilibrium NEET PYQs (1988–2026)

Solved Equilibrium PYQs

3 recent questions with answers. The full set of 134 is free to practise.

1. NEET 2026MediumEquilibrium Constants
   Q1

   Given below are certain reactions. Identify the reaction for which $K_p\ne K_C$.

   • AH₂O(g) + CO(g) ⇌ H₂(g) + CO₂(g)
   • BN₂(g) + 3H₂(g) ⇌ 2NH₃(g)
   • CH₂(g) + I₂(g) ⇌ 2HI(g)
   • DN₂(g) + O₂(g) ⇌ 2NO(g)

   Show answer & solution

   Correct answer: (B)

   $K_p=K_C(RT{)}^{\Delta n_g}$. For $K_p\ne K_C$,
   
   $\Delta n_g\ne 0$. Reaction (2): Δn_g = 2 - (1+3) = -2 ≠ 0.
2. NEET 2026MediumAcid-Base Equilibria
   Q2

   Phenolphthalein is used as an indicator for the titration of sodium hydroxide solution against a standard solution of oxalic acid. The colour change that is observed at an alkaline pH close to the equivalence point during this titration is:

   • Apinkish red to yellow
   • Byellow to pinkish red
   • Cpink to colourless
   • Dcolourless to pink

   Show answer & solution

   Correct answer: (D)

   Phenolphthalein is colourless in acid, pink in base. In base to acid
   
   titration, the change is colourless to pink at the endpoint.
3. NEET 2026HardBuffer Solutions
   Q3

   At 298 K, a certain buffer solution contains equal concentrations of X^- and HX. $K_b$ for X^- is 10^-10. What is the pH of this buffer solution?

   • A2
   • B4
   • C6
   • D10

   Show answer & solution

   Correct answer: (B)

   For acid HX,
   
   $$K_a=\frac{K_w}{K_b}=\frac{10^{-14}}{10^{-10}}=10^-⁴.$$
   
   pH = $p{K}_a$ + log([X^-]/[HX]) = 4 + log(1) = 4.

Topic-wise question count

Where NEET has asked from Equilibrium, most frequent first.

• Equilibrium Constants18
• Acid-Base Equilibria18
• Ionization Constants18
• pH Calculations17
• Buffer Solutions15
• Le Chatelier's Principle15
• Hydrolysis of Salts14
• Common Ion Effect13
• Solubility Product6

Year-wise Equilibrium questions in NEET

Number of questions from this chapter in each year's paper(s).