Physics-DPP-1-4.First Law of Thermodynamics, Calorimetry and Heat Transfer

PHYSICS Topic: First Law of Thermodynamics, Calorimetry and Heat Transfer Date: 1. A slab consists of two parallel layers of two different materials of same thickness having thermal conductivities K1 and K2. The equivalent conductivity of the combination is: (a) K + K (b) K1 + K2 (c) 2K1K2 K1 + K2 (d) 1 2 2 K1 + K2 2K1K2 2. Steam at 1000C is passed into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at 150C till the temperature of calorimeter and its contents rises to 800C. The mass of the steam condensed in kilogram is : (S = 103 cal/kg- 0C and L = 540  103 cal/kg) (a) 0.130 (b) 0.065 (c) 0.260 (d) 0.135 3. If a body cools down from 800C to 600C in 10 min when the temperature of the surrounding is 300C. Then, the temperature of the body after next 10 min will be : (a) 500C (b) 480C (c) 300C (d) none of these 4. Two similar rods are joined as shown in figure. Then temperature of junction is (assume no heat loss through lateral surface of rod and temperatures at the ends are shown in steady state) (a) 500C (b) 750C (c) 66.60C (d) 33.30C 5. Equal masses of three liquids A, B, & C have temperature 100C, 250C and 400C respectively. IfAand B are mixed, the mixture has temperature of 150C. If B and C are mixed, the mixture has temperature of 300C. IfA and C are mixed, the mixture will have a temperature of : (a) 160C (b) 200C (c) 250C (d) 290C 6. The latest heat of vaporisation of water is 2240 J. If work done in the process of vaporisations of 1 gram is 168 J, then increase in internal energy will be : (a) 1904 J (b) 2072 J (c) 2240 J (d) 2408 J 7. A spherical black body with a radius of 12 cm radiates 440 W power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be : (a) 440 (b) 1320 (c) 880 (d) 1760 çæ 5ö÷ çæ 7ö÷ 8. One mole of monoatomic gas çγ = ÷ is mixed with 1 mole of diatomic gas çγ = ÷. What will be the value of gama for the mixture è 3ø : è 5ø (a) 1.45 (b) 1.4 (c) 1.54 (d) 1.5 9. The temperature of inside and outside of refrigerator are 273 K and 303 K respectively. Assuming that refrigerator cycle is reversible, for every Joule of work done, the heat delivered to surrounding will be : (a) 50 J (b) 30 J (c) 10 J (d) 20 J 10. Two gases A and B having same pressure P, Volume V and temperature T are mixed. If the mixture has volume and temperature as V and T respectively, then pressure of mixture will be : (a) 4 P (b) 3 P (c) 2 P (d) P PHYSICS Topic: First Law of Thermodynamics, Calorimetry and Heat Transfer Date: Answer Key 1. (b) 2. (a ) 3. (b) 4. (a) 5. (a ) 6. (b ) 7. (d ) 8. (d ) 9. ( c ) 10. ( c )

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