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)
Molarity of a NaOH solution
Dissolve 8 g of NaOH (M = 40) in water to make 250 cm³ of solution.
moles = 8/40 = 0.2; volume = 0.25 dm³
Molarity = 0.2 / 0.25 = 0.8 M
Mass of solute for a given solution
Mass of glucose (M = 180) needed for 500 cm³ of 0.2 M solution.
moles = 0.2 × 0.5 = 0.1; mass = 0.1 × 180 = 18 g
Dilution calculation
What volume of 5 M HCl is needed to make 250 cm³ of 0.5 M HCl?
M₁V₁ = M₂V₂ → 5 × V₁ = 0.5 × 250 → V₁ = 125/5 = 25 cm³
Why does salt lower the freezing point of water?
Salt adds solute particles that interfere with ice formation, so a lower temperature is needed to freeze it — a colligative property (freezing-point depression). This is why salt is spread on icy roads.
Distinguish a colloid from a true solution
Shine a light beam through both. The colloid scatters the light, making the beam visible (the Tyndall effect); the true solution does not → the one showing the beam is the colloid.