Board-style MCQs and past-paper numericals in the BIEK / Sindh Board pattern. Tap an option to check yourself instantly. Solved numericals are at the bottom.
Multiple-choice questions
Solved numericals & self-assessment (past papers)
Boyle's law — new volume
A gas occupies 500 cm³ at 1 atm. Find its volume at 2.5 atm (constant T).
P₁V₁ = P₂V₂ → (1)(500) = (2.5)(V₂) → V₂ = 500/2.5 = 200 cm³
Charles's law — new temperature
A gas is 250 cm³ at 27 °C. At what temperature is its volume 300 cm³ (constant P)?
V₁/T₁ = V₂/T₂ → 250/300 = 300/T₂ → T₂ = 300 × 300/250 = 360 K = 87 °C
Ideal-gas equation — number of moles
How many moles of gas occupy 4.48 dm³ at STP (0 °C, 1 atm)?
n = PV/RT = (1 × 4.48)/(0.0821 × 273) = 0.2 mol (= 4.48/22.4)
Graham's law — relative diffusion rate
Compare the rates of diffusion of SO₂ (M=64) and CH₄ (M=16).
r(CH₄)/r(SO₂) = √(64/16) = √4 = 2 — methane diffuses twice as fast
Dalton's law — total pressure
A flask contains H₂ at 0.4 atm and N₂ at 0.3 atm and O₂ at 0.2 atm.
P_total = 0.4 + 0.3 + 0.2 = 0.9 atm