CBSE Class 11 Physics Thermal Properties of Matter MCQs Set D

Question. According to Newton’s law of cooling, the rate of cooling of a body is proportional to (Δθ)ⁿ, where Δθ is the difference of the temperature of the body and the surroundings, and n is equal to
(a) two
(b) three
(c) four
(d) one
Answer: d

Question. Two solid spheres, of radii R₁ and R₂ are made of the same material and have similar surfaces. The spheres are raised to the same temperature and then allowed to cool under identical conditions. Assuming spheres to be perfect conductors of heat, their initial rates of loss of heat are
(a) R²₁/R²₂
(b) R₁/R₂
(c) R₂/R₁
(d) R²₂/R²₁
Answer: a

Question. A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is
(a) Ec
(b) 2E/c
(c) E/c
(d) E/c²
Answer: b

Question. A metallic rod l cm long, A square cm in cross-section is heated through tºC. If Young’s modulus of elasticity of the metal is E and the mean coefficient of linear expansion is a per degree celsius, then the compressional force required to prevent the rod from expanding along its length is
(a) E A a t
(b) E A a t/(1 + at)
(c) E A a t/(1 – a t)
(d) E l a t
Answer: a

Question. A metal cube of length 10.0 mm at 0°C (273K) is heated to 200°C (473K). Given : its coefficient of linear expansion is 2 × 10^–5 K^–1. The percent change of its volume is
(a) 0.1
(b) 0.2
(c) 0.4
(d) 1.2
Answer: d

Question. A metallic bar is heated from 0ºC to 100ºC. The coeficient of linear expansion is 10^–5 K^–1. What will be the percentage increase in length?
(a) 0.01%
(b) 0.1%
(c) 1%
(d) 10%
Answer: b

Question. Which of the following is not close to a black body?
(a) Black board paint
(b) Green leaves
(c) Black holes
(d) Red roses
Answer: a

Question. The temperature of the Sun is measured with
(a) platinum thermometer
(b) gas thermometer
(c) pyrometer
(d) vapour pressure thermometer.
Answer: c

Question. If a bar is made of copper whose coefficient of linear expansion is one and a half times that of iron, the ratio of force developed in the copper bar to the iron bar of identical lengths and cross-sections, when heated through the same temperature range (Young’s modulus of copper may be taken to be equal to that of iron) is
(a) 3/2
(b) 2/3
(c) 9/4
(d) 4/9
Answer: a

Question. In a surrounding medium of temperature 10°C, a body takes 7 min for a fall of temperature from 60°C to 40°C. In what time the temperature of the body will fall from 40°C to 28°C?
(a) 7 min
(b) 11 min
(c) 14 min
(d) 21 min
Answer: a

Question. A beaker contains 200 g of water. The heat capacity of beaker is equal to that 20 g of water. The initial temperature of water in the beaker is 20°C . If 440 g of hot water at 92°C is poured in, the final temperature, neglecting radiation loss, will be
(a) 58°C
(b) 68°C
(c) 73°C
(d) 78°C
Answer: b

Question. In order that the heat flows from one part of a solid to another part, what is required?
(a) Uniform density
(b) Temperature gradient
(c) Density gradient
(d) Uniform temperature
Answer: b

Question. The sprinkling of water slightly reduces the temperature of a closed room because
(a) temperature of water is less than that of the room
(b) specific heat of water is high
(c) water has large latent heat of vaporisation
(d) water is a bad conductor of heat
Answer: c

Question. Which of the following circular rods, (given radius r and length l) each made of the same material and whose ends are maintained at the same temperature will conduct most heat?
(a) r = 2r₀; l = 2l₀
(b) r = 2r₀; l = l₀
(c) r = r₀; l = 2l₀
(d) r = r₀; l = l₀
Answer: b

Question. Two rods P and Q of same length and same diameter having thermal conductivity ratio 2 : 3 joined end to end. If temperature at one end of P is 100°C and at one and of Q 0°C, then the temperature of the interface is
(a) 40°C
(b) 50°C
(c) 60°C
(d) 70°C
Answer: a

Question. Steam is passed into 22 gm of water at 20ºC. The mass of water that will be present when the water acquires a temperatue of 90ºC (Latent heat of steam is 540 cal/g) is
(a) 24.83 gm
(b) 24 gm
(c) 36.6 gm
(d) 30 gm
Answer: a

Question. A body of mass 5 kg falls from a height of 20 metres on the ground and it rebounds to a height of 0.2 m. If the loss in potential energy is used up by the body, then what will be the temperature rise? (specific heat of material = 0.09 cal gm^–1 ºC^–1)
(a) 0ºC
(b) 4ºC
(c) 8ºC
(d) None of these
Answer: d

Question. Two identical rods of copper and iron are coated with wax uniformly. When one end of each is kept at temperature of boiling water, the length upto which wax melts are 8.4 cm amd 4.2 cm, respectively. If thermal conductivity of copper is 0.92, then thermal conductivity of iron is
(a) 0.23
(b) 0.46
(c) 0.115
(d) 0.69
Answer: a

Question. No other thermometer is suitable as a platinum resistance thermometer to measure temperatures in the entire range of
(a) –50ºC to + 350ºC
(b) –200ºC to + 600ºC
(c) 0ºC to 100ºC
(b) 100ºC to 1500ºC
Answer: b

Question. The rate of radiation of a black body at 0ºC is E joule per sec. Then the rate of radiation of this black body at 273ºc will be
(a) 16 E
(b) 8 E
(c) 4 E
(d) E
Answer: a

Question. A mountain climber finds that water boils at 80ºC. The temperature of this boiling water is…… Fahrenheit
(a) 50º
(b) 150º
(c) 176º
(d) 200º
Answer: c

Question. 100 g of ice is mixed with 100 g of water at 100ºC. What will be the final temperature of the mixture ?
(a) 13.33ºC
(b) 20ºC
(c) 23.33ºC
(d) 40ºC
Answer: a

Question. Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 min and 35 min, respectivley. The ratio of coefficients of thermal conduction of the metals is
(a) 4 : 7
(b) 7 : 4
(c) 25 : 16
(d) 16 : 25
Answer: b

Question. A partition wall has two layers A and B, in contact, each made of a different material. They have the same thickness but the thermal conductivity of layer A is twice that of layer B. If the steady state temperature difference across the wall is 60 K, then the corresponding difference across the layer A is
(a) 10 K
(b) 20 K
(c) 30 K
(d) 40 K
Answer: b

Question. The spectral energy distribution of the sun (temperature 6050 K) is maximum at 4753 Å. The temperature of a star for which this maximum is at 9506 Å is
(a) 6050 K
(b) 3025 K
(c) 12100 K
(d) 24200 K
Answer: b

Question. The coefficient of apparent expansion of mercury in a glass vessel is 153 × 10^–6/ºC and in a steel vessel is 144 × 10–6/ºC. If a for steel is 12 × 10^–6/ºC, then, that of glass is
(a) 9 × 10^–6/ºC
(b) 6 × 10^–6/ºC
(c) 36 × 10^–6/ºC
(d) 27 × 10^–6/ºC
Answer: a

Question. A beaker contains 200 gm of water. The heat capacity of the beaker is equal to that of 20 gm of water. The initial temperatue of water in the beaker is 20ºC. If 440 gm of hot water at 92ºC is poured in it, the final temperature, neglecting radiation loss, will be nearest to
(a) 58ºC
(b) 68ºC
(c) 73ºC
(d) 78ºC
Answer: b

Question. When a body is heated, which colour corresponds to high temperature
(a) red
(b) yellow
(c) white
(d) orange
Answer: c

Question. A rectangular block is heated from 0ºC to 100ºC. The percentage increase in its length is 0.10%. What will be the percentage increase in its volume?
(a) 0.03%
(b) 0.10%
(c) 0.30%
(d) None of these
Answer: c

Question. Steam at 100ºC is passed into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at 15ºC till the temperature of the calorimeter and its contents rises to 80ºC.The mass of the steam condensed in kg is
(a) 0.130
(b) 0.065
(c) 0.260
(d) 0.135
Answer: a

Question. A pendulum clock is 5 seconds fast at temperature of 15ºC and 10 seconds slow at a temperature of 30ºC. At what temperature does it give the correct time? (take time interval = 24 hours)
(a) 18ºC
(b) 20ºC
(c) 22ºC
(d) 25ºC
Answer: c

Question. A vessel completely filled with a liquid is heated. If a and g represent coefficient of linear expansion of material of vessel and coefficient of cubical expansion of liquid respectively, then the liquid will not overflow if
(a) Υ = 3 a
(b) Υ > 3 a
(c) Υ < 3 a
(d) Υ < 3 a
Answer: d

Question. Two bodies A and B are placed in an evacuated vessel maintained at a temperature of 27ºC. The temperature of A is 327ºC and that of B is 227ºC. The ratio of heat loss from A and B is about
(a) 2 : 1
(b) 1 : 2
(c) 4 : 1
(d) 1 : 4
Answer: a

Question. 5 kg of water at 10°C is added to 10 kg of water at 40°C. Neglecting heat capacity of vessel and other losses, the equilibrium temperature will be
(a) 30°C
(b) 25°C
(c) 35°C
(d) 33°C
Answer: a

Question. A slab consists of two parallel layers of copper and brass of the same thickness and having thermal conductivities in the ratio 1 : 4. If the free face of brass is at 100°C and that of copper at 0°C, the temperature of interface is
(a) 80°C
(b) 20°C
(c) 60°C
(d) 40°C
Answer: a

Question. 540 g of ice at 0°C is mixed with 540 g of water at 80°C. The final temperature of mixture is
(a) 0°C
(b) 40°C
(c) 80°C
(d) less than 0°C
Answer: a

Question. A black body at 227°C radiates heat at the rate of 7 cals/ cm²s. At a temperature of 727°C, the rate of heat radiated in the same units will be
(a) 50
(b) 112
(c) 80
(d) 60
Answer: b

Question. Solar radiation emitted by sun resembles that emitted by a black body at a temperature of 6000 K. Maximum intensity is emitted at wavelength of about 4800 Å. If the sun were to cool down from 6000 K to 3000 K, then the peak intensity would occur at a wavelength
(a) 4800 Å
(b) 9600 Å
(c) 2400 Å
(d) 19200 Å
Answer: b

Question. A bucket full of hot water is kept in a room and it cools from 75ºC to 70ºC in T₁ minutes, from 70ºC to 65ºC in T₂ minutes and from 65ºC to 60ºC in T₃ minutes. Then
(a) T₁ = T₂ = T₃
(b) T₁ < T₂ < T₃
(c) T₁ > T₂ > T₃
(d) T₁ < T₂ > T₃
Answer: b

Question. The fastest mode of transfer of heat is
(a) conduction
(b) convection
(c) radiation
(d) None of these
Answer: c