Grades/ Grade 11/ Physics/ Heat & Thermodynamics/Practice
Class XI · Physics · Unit 11 · Practice

Heat & Thermodynamics — practice

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.

Score 0 / 0Attempted 0 · tap any option to answer

Multiple-choice questions

Solved numericals (past papers)

Scale conversion — heatwave temperature
A weather report says 113 °F. Convert to °C and K.
T(°C) = (5/9)(113 − 32) = (5/9)(81) = 45 °C
T(K) = 45 + 273 = 318 K
Linear expansion of a steel rail
A 30 m steel rail (α = 1.2 × 10⁻⁵ K⁻¹) is heated from 18 °C to 48 °C.
ΔL = αLΔT = (1.2 × 10⁻⁵)(30)(30) = 1.08 × 10⁻² m = 10.8 mm — hence the expansion gap.
Ice at 0 °C to steam at 100 °C (full heating curve)
m = 0.1 kg; L_f = 3.36 × 10⁵ J/kg; c = 4200 J·kg⁻¹·K⁻¹; L_v = 2.26 × 10⁶ J/kg.
melt: Q₁ = mL_f = 3.36 × 10⁴ J
warm 0→100 °C: Q₂ = mcΔT = 4.2 × 10⁴ J
boil: Q₃ = mL_v = 2.26 × 10⁵ J
total = 3.02 × 10⁵ J ≈ 302 kJ
First law + engine efficiency
(a) A gas absorbs 800 J and does 300 J of work: ΔU = Q − W = 800 − 300 = +500 J
(b) An engine takes 1000 J and rejects 600 J per cycle:
W = 1000 − 600 = 400 J → η = W/Q₁ = 400/1000 = 40%
← Chapter hub 📖 Lecture 🎬 Interactive lecture ← All chapters