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Equilibrium — NEET & JEE Chemistry MCQs

30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.

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Sample questions from this chapter

What is true when a reversible reaction reaches dynamic equilibrium?
  1. Forward and reverse rates are equal while both reactions continue ✓
  2. Reactant and product concentrations become equal
  3. Molecular collisions stop but concentrations remain fixed
  4. The forward reaction finishes before the reverse reaction begins
Answer: A. Dynamic equilibrium means equal opposing rates, so macroscopic composition is constant despite continuing molecular conversion. Equal rates must not be confused with equal concentrations.
Why not B: Equilibrium requires constant concentrations, not equal numerical concentrations of reactants and products.
Why not C: Microscopic reactions and collisions continue; only the net composition change vanishes.
Why not D: Forward and reverse processes occur simultaneously and approach equal rates.
For H2 + I2 ⇌ 2HI, equilibrium concentrations are 0.20 M, 0.20 M and 0.80 M, respectively. What is Kc?
  1. 4.0
  2. 8.0
  3. 16 ✓
  4. 20
Answer: C. Kc = [HI]^2/([H2][I2]) = 0.80^2/(0.20×0.20) = 16. The 4.0 trap is the classic dropped product coefficient.
Why not A: This uses [HI]/([H2][I2]) and drops the exponent 2 on HI.
Why not B: This divides 0.80 by only one reactant concentration, omitting the other.
Why not D: This divides [HI] by the product 0.04 and still omits the square.
For CO + H2O ⇌ CO2 + H2, Kc = 4.00. Initially [CO] = [H2O] = 0.100 M and no products are present. What are the equilibrium concentrations in the order CO, H2O, CO2, H2?
  1. 0.0333 M, 0.0333 M, 0.0667 M, 0.0667 M ✓
  2. 0.0500 M, 0.0500 M, 0.0500 M, 0.0500 M
  3. 0.0667 M, 0.0667 M, 0.0333 M, 0.0333 M
  4. 0.0200 M, 0.0200 M, 0.0800 M, 0.0800 M
Answer: A. Let each product be x: K = [x/(0.100−x)]^2 = 4, so x/(0.100−x) = 2 and x = 0.0667 M. Reactants are 0.0333 M.
Why not B: This assumes equal reactant and product concentrations imply K = 4, but that composition gives K = 1.
Why not C: This uses x/(0.100−x) = 1/2, taking the reciprocal of √K.
Why not D: This sets product-to-reactant concentration ratio equal to K = 4 instead of √K = 2.

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Other NEET Chemistry chapters

Some Basic Concepts of ChemistryStructure of AtomClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular StructureThermodynamicsRedox Reactions

All 19 chapters →

Questions

How many NEET and JEE questions are there on Equilibrium?

This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 11 chapter.

Is this NEET and JEE Chemistry chapter test free?

Yes. Every chapter test is free with no login, and you get your all-India rank on every one. Nothing on the site is on sale right now.

Do the questions explain the wrong options?

Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.