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)
Heat absorbed by water (q = mcΔT)
How much heat raises 200 g of water by 15 °C? (c = 4.18 J g⁻¹ °C⁻¹)
q = mcΔT = 200 × 4.18 × 15 = 12 540 J = 12.54 kJ
ΔH by Hess's law
Given: C + O₂ → CO₂, ΔH = −393 kJ; CO + ½O₂ → CO₂, ΔH = −283 kJ.
For C + ½O₂ → CO: ΔH = (−393) − (−283) = −110 kJ
ΔH from bond energies
Bonds broken total 1650 kJ; bonds formed total 1800 kJ.
ΔH = Σ(broken) − Σ(formed) = 1650 − 1800 = −150 kJ (exothermic)
Temperature change from heat released
8.36 kJ is released into 250 g of water. Find ΔT.
q = mcΔT → 8360 = 250 × 4.18 × ΔT → ΔT = 8360 / 1045 = 8 °C
Classify reactions as exo- or endothermic
Combustion of methane (ΔH = −890 kJ) → exothermic
Thermal decomposition of CaCO₃ (ΔH = +178 kJ) → endothermic