Thermal Properties of Matter — Previous-Year Questions

Q1. A steel rod (α = 12×10⁻⁶/K) of length 100 m heated by 50°C. ΔL:

Q2. A metal ring with a hole is heated. The hole diameter:

Q3. Why are gaps left between rails on a railway track?

Q4. If two metals are bonded into a strip and heated: bending occurs because:

Q5. Thermal stress in a body constrained from expanding:

Q1. A copper plate of area 100 cm², α = 17×10⁻⁶/K, heated by 100°C. ΔA:

Q2. Relation between area-expansion β and linear-expansion α for an isotropic solid:

Q3. A circular hole in an iron plate is heated. The area of the hole:

Q4. If linear coefficient is 11×10⁻⁶/K, area coefficient is:

Q5. A square sheet has each side increase by 1%. Area increase:

Q1. A solid cube of side 10 cm and α = 24×10⁻⁶/K is heated by 100°C. ΔV:

Q2. γ for an isotropic solid is:

Q3. Volume expansion of an ideal gas at constant pressure depends on temperature as:

Q4. A 1-litre container of liquid (γ_L = 4×10⁻⁴/K) made of glass (γ_g = 27×10⁻⁶/K). Apparent expansion per degree:

Q5. If α of iron is 12×10⁻⁶/K, γ (volume coefficient) is:

Q1. Density of water is MAXIMUM at:

Q2. Volume increase when water freezes to ice:

Q3. Lakes in cold regions freeze:

Q4. What fraction of an iceberg is ABOVE water?

Q5. Water's anomalous expansion below 4°C is due to:

Q1. Heat needed to raise 0.5 kg of water from 20°C to 80°C:

Q2. Why does water heat slowly compared to metals?

Q3. Heat is:

Q4. 1 calorie equals approximately:

Q5. Temperature is a measure of:

Q1. 100 g water at 80°C mixed with 200 g water at 20°C. Final T:

Q2. Two bodies at different temperatures placed in contact. Heat flows:

Q3. A 100 g block of metal at 100°C dropped into 200 g of water at 20°C; final T = 24°C. c of metal:

Q4. If the metal in (c) had been gold (c ≈ 130), what final T?

Q5. Calorimetry assumes:

Q1. A slab of conductivity k = 50 W/m·K, area 1 m², thickness 0.1 m, with ΔT = 30 K. Heat current:

Q2. Why are metals good conductors of heat?

Q3. Heat conduction in a vacuum is:

Q4. Two slabs of same area in SERIES with R₁ = 2 K/W and R₂ = 3 K/W. Total R:

Q5. Thermal conductivity of copper is approximately:

Q1. Why does a metal floor feel colder than a wooden floor at the same temperature?

Q2. Approximate k of air at room temperature:

Q3. Diamond's thermal conductivity is approximately:

Q4. Double-pane windows insulate well because:

Q5. Wiedemann-Franz law states k/σ for metals is proportional to:

Q1. Convection occurs in:

Q2. Natural convection is driven by:

Q3. Newton's law of cooling assumes the medium is:

Q4. Heat radiator placed at the floor heats a room because:

Q5. Convection coefficient h for forced air vs natural air:

Q1. Power radiated by a black sphere (ε = 1) of area 1 m² at 1000 K:

Q2. If T doubles, radiated power changes by factor:

Q3. Peak wavelength of sunlight from T = 6000 K (Wien's law):

Q4. Heat radiation requires:

Q5. Emissivity of a perfect black body:

Q1. A body cools from 80°C to 60°C in 5 min in 20°C surroundings. Time to cool from 60°C to 40°C:

Q2. Newton's law of cooling assumes:

Q3. A cooling curve fits T(t) = 25 + 75·e^(−0.1t) (in min). Initial T:

Q4. Faster cooling for the same body occurs when:

Q5. Cooling curve eventually approaches:

Q1. Heat to melt 1 kg ice at 0°C (L_f = 334 kJ/kg):

Q2. While ice melts at 0°C, its temperature:

Q3. Heat to convert 1 kg of water at 100°C to steam at 100°C:

Q4. Heat to convert 1 kg ice at −10°C to water at 0°C:

Q5. Sweating cools the body because: