Board-style MCQs and past-paper numericals in the BIEK / Sindh Board pattern. Tap an option to check yourself instantly. Solved questions are at the bottom.
Multiple-choice questions
Solved numericals & self-assessment (past papers)
Write the Kc expression for N₂ + 3H₂ ⇌ 2NH₃
Kc = [NH₃]² / ([N₂][H₂]³)
Δn = 2 − 4 = −2, so Kp = Kc(RT)⁻² and the units of Kc are mol⁻² dm⁶.
Calculate Kc for H₂ + I₂ ⇌ 2HI
At equilibrium [H₂] = 0.2, [I₂] = 0.2, [HI] = 1.6 mol/dm³.
Kc = [HI]² / ([H₂][I₂]) = (1.6)² / (0.2 × 0.2) = 2.56 / 0.04 = 64
Le Chatelier — Haber process at higher temperature
N₂ + 3H₂ ⇌ 2NH₃ is exothermic. Raising the temperature shifts equilibrium in the endothermic (reverse) direction → less NH₃, and Kc decreases.
Effect of increasing pressure on 2SO₂ + O₂ ⇌ 2SO₃
Reactant side = 3 moles of gas, product side = 2 moles. Increasing pressure shifts to the side with fewer moles → forward (more SO₃).
For which reaction is Kp = Kc?
Kp = Kc when Δn = 0 (equal gas moles both sides). e.g. H₂ + I₂ ⇌ 2HI (Δn = 2 − 2 = 0) → Kp = Kc.