NEET Physics Thermal Properties of Matter Online Test Set A

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2. A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be

3. Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are K₁ and K₂. The thermal conductivity of the composite rod will be

4. Two spheres of different materials one with double the radius and one-fourth wall thickness of the other are filled with ice. If the time taken for complete melting of ice in the larger sphere is 25 minute and for smaller one is 16 minute, the ratio of thermal conductivities of the materials of larger spheres to that of smaller sphere is

5. Steam is passed into 22 g of water at 20°C. The mass of water that will be present when the water acquires a temperature of 90°C is (Latent heat of steam is 540 cal/gm)

6. A piece of ice falls from a height h so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is : [Latent heat of ice is 3.4 × 10⁵ J/kg and g = 10 N/kg]

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9. A solid body of constant heat capacity 1 J/°C is being heated by keeping it in contact with reservoirs in two ways :
(i) Sequentially keeping in contact with 2 reservoirs such that each reservoir supplies same amount of heat.
(ii) Sequentially keeping in contact with 8 reservoirs such that each reservoir supplies same amount of heat.
In both the cases body is brought from initial temperature 100°C to final temperature 200°C. Entropy change of the body in the two cases respectively is :

10. The diagram below shows the change in the length X of a thin uniform wire caused by the application of stress F at two different temperatures T₁ and T₂. The variation shown suggests that

11. The rate of heat flow through the cross-section of the rod shown in figure is (T₂ > T₁ and thermal conductivity of the material of the rod is K)

12. The value of coefficient of volume expansion of glycerine is 5 × 10^-4 K^-1. The fractional change in the density of glycerine for a rise of 40°C in its temperature, is:

13. Three rods of Copper, Brass and Steel are welded together to form a Y shaped structure. Area of cross - section of each rod = 4 cm². End of copper rod is maintained at 100ºC where as ends of brass and steel are kept at 0ºC. Lengths of the copper, brass and steel rods are 46, 13 and 12 cms
respectively. The rods are thermally insulated from surroundings excepts at ends. Thermal conductivities of copper, brass and steel are 0.92, 0.26 and 0.12 CGS units respectively. Rate of heat flow through copper rod is:

14. A crystal has a coefficient of expansion 13×10^–7 in one direction and 231 × 10^–7 in every direction at right angles to it. Then the cubical coefficient of expansion is

15. If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be

16. Certain quantity of water cools from 70°C to 60°C in the first 5 minutes and to 54°C in the next 5 minutes. The temperature of the surroundings is:

17. Steam at 100°C is passed into 20 g of water at 10°C. When water acquires a temperature of 80°C, the mass of water present will be: [Take specific heat of water = 1 cal g^{– 1} °C^{– 1} and latent heat of steam = 540 cal g^{– 1}]

18. A sphere, a cube and a thin circular plate, all of same material and same mass are initially heated to same high temperature

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20. Heat is associated with

21. As the temperature is increased, the period of a pendulum

22. An aluminium sphere is dipped into water. Which of the following is true?

23. The graph between two temperature scales A and B is shown in figure between upper fixed point and lower fixed point there are 150 equal division on scale A and 100 on scale B. The relationship for conversion between the two scales is given by

24. A uniform metallic rod rotates about its perpendicular bisector with constant angular speed. If it is heated uniformly to raise its temperature slightly

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