Practise 36 real Federal Board questions on Chemical Equilibrium from 2023 to 2026. See the answer and explanation as soon as you answer.
Chemical Equilibrium is one of the 19 main chapters in our Federal Board FSC Chemistry question bank (11th class), and about 7% of its real questions come from it. Tayyari Karo has 36 real questions on this chapter from 2023 to 2026; 11 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 21 medium, 13 hard, 2 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
pH value of aqueous solution of CH₃COONa will be:
Answer: A. pH>7
CH₃COONa is the salt of a weak acid (CH₃COOH) and strong base (NaOH); its acetate ion hydrolyzes to make the solution basic, pH>7.
The following equilibrium will NOT be shifted in the forward direction by: N₂+3H₂⇌2NH₃+Δ
Answer: A. Increasing temperature
This is an exothermic forward reaction, so raising the temperature shifts equilibrium backward (Le Chatelier), not forward; the other three options all favour the forward direction.
If solubility of a salt MX is 2×10⁻² mol/dm³, what will be the value of Ksp if salt dissociates into one cation (M⁺) and one anion (X⁻)?
Answer: C. 4×10⁻⁴
Ksp = [M⁺][X⁻] = s² = (2×10⁻²)² = 4×10⁻⁴.
The strong conjugate base in the given is:
Answer: A. CO₃⁻²
CO₃²⁻ is the conjugate base of the weak acid HCO₃⁻, making it the strongest base among these (conjugate bases of strong acids like HNO₃, HCl are very weak bases).
"Zn" acts as anode in Daniel cell but acts as cathode when coupled with Aluminium electrode. This is because:
Answer: B. E° of Zn > E° of Al
The electrode with the more negative (lower) standard reduction potential is oxidized (anode). Since E°(Al) < E°(Zn), Al becomes the anode and Zn the cathode when paired with Al.
If 25 dm³ of 1 mol.dm⁻³ of HNO₃ is added to 50 dm³ of 0.5 mol.dm⁻³ of KOH solution, what would be the pH of the resulting solution?
Answer: D. 07
Moles HNO₃ = 25×1 = 25 mol; moles KOH = 50×0.5 = 25 mol. Equal moles of strong acid and strong base neutralize exactly, giving the neutral salt KNO₃, pH = 7.
State the necessary conditions for equilibrium.
1. The system must be closed (no matter enters or leaves).
2. The system must be at constant temperature.
3. The rate of the forward reaction must equal the rate of the reverse reaction, so the concentrations of reactants and products remain constant (dynamic equilibrium) — macroscopically observable properties (color, pressure, concentration) stop changing.
Derive the relation to determine the Acid dissociation constant Ka for the following dissociation equation for an acid (HX): HX+H₂O⇌H₃O⁺+X⁻
For the equilibrium HX + H₂O ⇌ H₃O⁺ + X⁻, the equilibrium expression is Kc = [H₃O⁺][X⁻]/([HX][H₂O]).
Since water is in large excess/nearly constant concentration in dilute solution, its concentration is absorbed into a new constant:
Ka = [H₃O⁺][X⁻]/[HX], called the acid dissociation constant.
| Session | Questions |
|---|---|
| 2026 Annual | 5 |
| 2025 1st Annual | 8 |
| 2025 2nd Annual | 6 |
| 2024 Annual | 10 |
| 2023 Annual | 7 |
36 real Federal Board (FBISE) Chemistry questions on Chemical Equilibrium from 2023 to 2026, for 11th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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