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1.Temperature & heat, , Temperature, Thermometry, , Level 0, 1. At what temperature does the temperature in Celsius, and Fahrenheit equalize, (a) -400, (b) 400, 0, (c) 36.6, (d) 380, 2. The graph AB shown in figure is a plot of, temperature of a body in degree Celsius and degree, Fahrenheit. Then

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(a) slope of line AB is 9/5, (b) slope of line AB is 5/9, (c) slope of line AB is 1/9, (d) slope of line AB is 3/9, 3. Two thermometers X and Y have ice points marked, at 150 and 250 and steam points marked as 750 and, 1250 respectively. When thermometer X measures, the temperature of a bath as 600 on it, what would, thermometer Y red when it is used to measure the, temperature of the same bath?, (a) 600, (b) 750, 0, (c) 100, (d) 900, 4. One a new scale of temperature (which is linear) and, called the W scale, the freezing and boiling points of, water are 390W and 2390W respectively. What will, be the temperature on the new scale, corresponding, to a temperature of 390C on the Celsius scale?, (a) 2000W, (b) 1390W, (c) 780W, (d) 1170 W, 5. Oxygen boils at -1830C. this temperature is, approximately in Fahrenheit is:, (a) -3290F, (b) -2610F, 0, (c) -215 F, (d) -2970F, , 8. The volume of a metal sphere increases by 0.15%, when its temperature is raised by 240C. The, coefficient of linear expansion of metal is:, (a) 2.5 x 10-5 / 0C (b) 2.0 x 10-5 /0C, (c) -1.5 x 10-5/0C (d) 1.2 x 10-5/0C, 9. A copper rod of 88 cm and an aluminium rod of, unknown length have their increase in length is same, & independent of increase in temperature. The, length of aluminium rod is: (αcu= 1.7 x 10-5 /0C, αal=, 2.2 x 10-5 /0C ), (a) 6.8 cm, (b) 113.9 cm, (c) 88 cm, (d) 68 cm, 10. Two rods A and B of identical dimensions are at, temperature 300C. If A is heated upto 1800C and B, upto T0C, then the new lengths are the same. If the, ratio of the coefficients of linear expansion of A and, B is 4:3, then the value of T is:(a) 2700.C, (b) 2300C, 0, (c) 250 C, (d) 2000C, , Heat & Calorimetry, , Thermal expansion, , Level 0, 11. A solid material is supplied with heat at a constant, rate. The temperature of material is changing with, heat input as shown in the figure. What does slope, DE represent, , Level 0, 6. A steel tape gives correct measurement at 200C. A, piece of wood is being measured with the steel tape, at 00C. The reading is 25 cm on the tape, the real, length of the given piece of wood must be:, (a) 25 cm, (b) <25 cm, (c) >25 cm, (d) can not say, 7. Suppose there is a hole in a copper plate. On heating, the plate, diameter of hole, would:, (a) always increase, (b) always decrease, (c) always remain the same (d) none of these, , (a) latent heat of liquid, (b) latent heat of vapour, (c) heat capacity of vapour, (d) Inverse of heat capacity of vapour, 12. The graph shown in the figure represent change in, the temperature of 5 kg of a substance as it absorbs, heat at a constant rate of 42 kJ min-1. The latent heat, of vaporization of the substance is:

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13., , 14., , 15., , 16., , 17., , 18., , 19., , (a) 630 kJ kg-1, (b) 126 kJ kg-1, (c) 84 kJ kg-1, (d) 12.6 kJ kg-1, A block of mass 2.5 kg is heated to temperature of, 5000C and placed on a large ice block. What is the, maximum amount of ice that can melt (approx)., Specific heat for the body = 0.1 Cal/gm0C., (a) 1 kg, (b) 1.5 kg, (c) 2 kg, (d) 2.5 kg, If 10 gm ice at 00C is mixed with 10 gm water at, 200C, the final temperature will be:, (a) 500C, (b) 100C, 0, (c) 0 C, (d) 150C, Calorie is defined as the amount of heat required to, raise temperature of 1g of water by 10C and it is, defined under which of the following conditions:, (a) From 14.50C to 15.50C at 760 mm of Hg, (b) From 98.50C to 99.50C at 760 mm of Hg, (c) From 13.50C to 14.50C at 76 mm of Hg, (d) From 3.50C to 4.50C at 76 mm of Hg, How much ice at 00C will be melted by 1g of steam?, (Latent heat of ice = 80 cal/g and latent heat of, steam = 540 cal/g):, (a) 1g, (b) 2g, (c) 4g, (d) 8g, A liquid of mass m and specific heat c is heated to a, temperature 2T. Another liquid of mass m/2 and, specific heat 2c is heated to a temperature T. If these, two liquids are mixed, the resulting temperature of, the mixture is:, (a) (2/3)T, (b) (8/5)T, (c) (3/5) T, (d) (3/2)T, Two liquids A and B are at 320C and 240C. When, mixed in equal masses the temperature of the, mixture is found to be 280C. Their specific heats are, in the ratio of:, (a) 3 : 2, (b) 2 : 3, (c) 1 : 1, (d) 4 : 3, Liquid oxygen at 50K is heated to 300K at constant, pressure of 1 atm. The rate of heating is constant., Which one of the following graph represents the, variation of temperature with time?, , Ans c, 20. Ice at -200C os added to 50g of water at 400C. When, the temperature of the mixture reaches 00C, it is, found that 20 g of ice is still unmelted. The amount, of ice added to the water was close to (Specific heat, of water = 4.2 J/g/0C), Specific heat of Ice = 2.1 J/g/0C, Heat of fusion of water at 00C = 334 J/g, (a) 50g, (b) 40g, (c) 60g (d) 100g, Level 1, 21. Two identical bodies are made of a material for, which the heat capacity increases with temperature., One of these is at 1000C, while the other one is at, 00C.. If the two bodies are brought into contact, then,, assuming no heat loss, the final common, temperature is, (a) 00C, (b) 500C, 0, (c) More than 50 C, (d) less than 500C but greater than 00C, 22. 2 litre water at 270C is heated by a 1kW heater in an, open container. On an average heat is lost to, surroundings at the rate 160 J/s. The time required, for the temperature to reach 770C is, (a) 8 min 20 sec, (b) 10 min, (c) 7 min, (d) 14 min, 23. Steam at 1000C is added slowly to 1400 gm of water, at 160C until the temperature of water is raised to, 800C. The mass of steam required to do this is (LV =, 540 cal/gm):, (a) 160 gm, (b) 125 mg, (c) 250 gm, (d) 320 gm, 24. Steam at 1000C is passed into 20g of water at 100C., When water acquires a temperature of 800C, the, mass of water present will be: [Take specific heat of, water = 1 cal g-1 0C-1], (a) 24g, (b) 31.5 g, (c) 42.5 g, (d) 22.5 g, Heat & Mechanical Energy, Level 0, 25. A body of mass 5 kg falls from a height of 30 metre., If its all mechanical energy is changed into heat,, then heat produced will be:, (a) 350 cal, (b) 150 cal

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(c) 60 cal, (d) 6 cal, 26. The height of a waterfall is 84 metre. Assuming that, the entire kinetic energy of falling water is converted, into heat, the rise in temperature of the water will be, (g = 9.8 m/s2, J = 4.2 joule/cal), (a) 0.196 0C, (b) 1.960 0C, 0, (c) 0.96 C, (d) 0.01960C, 27. In a water-fall the water falls from a height of 100m., If the entire K.E. of water is converted into heat, the, rise in temperature of water will be, (a) 0.230C, (b) 0.460C, (c) 2.30C, (d) 0.0230C, 28. 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 x 105 J/kg and g = 10 N/kg], (a) 34 km, (b) 544 km, (c) 136 km, (d) 68 km, 29. A massless spring (k = 800 N/m), attached with a, mass (500g) is completely immersed in 1 kg of, water. The spring is stretched by 2 cm and released, so that it starts vibrating. What would be the order of, magnitude of the change in the temperature of water, when the vibrations stop completely? (Assume that, the water container and spring receive negligible, heat and specific heat of mass = 400 J/kg K, specific, heat of water = 4184 J/kg K), (a) 10-3 K, (c) 10-1 K, , (b) 10-4 K, (d) 10-5 K, , 2. Kinetic theory of gas, , KINETIC THEORY OF GASES:, , Gas Laws, Ideal gas equation, , Level 0, 1. A real gas behaves like an ideal gas if its, (a) Pressure and temperature are both high, (b) pressure and temperature are both low, (c) pressure is high and temperature is low, (d) pressure is low and temperature is high, 2. When temperature of a gas, contained in closed, vessel increased by 50C, its pressure increases by 1%, The original temperature of the gas was, approximately:, (a) 5000 C, (b) 2730C, 0, (c) 227 C, (d) 500 C, 3. Two gases of equal molar mass are in thermal, equilibrium If Pa, Pb and Va and Vb are their, respective pressure an volumes, then which relation, is true:

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(a) Pa  Pb , Va  Vb, 4., , 5., , 6., , 7., , 8., , (b) Pa  Pb , Va  Vb, , (c) Pa / Pb , Vb / Vb, (d) Pa Va  Pb Vb, Equal volume of H2, O2 and He gases are at same, temperature and pressure. Which of these will have, large number of molecules:, (a) H2, (b) O2, (c) He, (d) All the gas will have same number of molecules, A box contains N molecules of a gas. If the number, of molecules is doubled, then the pressure will:, (a) Decrease, (b) Be same, (c) Be doubled, (d) Get tripled, Root mean square velocity for a certain di-atomic, gas at room temperature 270C is found to be 1930, m/sec. The gas is =, (a) H2, (b) O2, (c) F2, (d) Cl2, Relation PV = RT is given for following condition, for real gas (a) High temperature and high density, (b) Low temperature and low density, (c) High temperature and low density, (d) low temperature and high density, The root mean square velocity of a gas molecule of, mass m at a given temperature is proportional to, (a) m0, (b) m, (c), , m, , (d), , 1, m, , 9. The equation of state for 5g of oxygen at a pressure, p and temperature T, when occupying a volume V,, will be:- (where R is the gas constant), (a) PV = 5 RT, (b) PV = (5/2)RT, (c) PV = (5/16)RT (d) PV = (5/32) RT, 10. On increasing the temperature of a gas filled in a, closed container by 10C its pressure increases by, 0.4% initial temperature of the gas is –, (a) 250C, (b) 2500 C, (c) 250 K, (d) 25000 C, 11. The pressure exerted by a gas in P0. If the mass of, molecules becomes half and their velocities become, double the pressure will become, (a), , P0, 2, , (b) P0, , (c) 2 P0, (d) 4 P0, 12. A gas is at 00C. Upto what temperature the gas is to, be heated so that the root mean square velocity of its, molecules be doubled., (a) 2730C, (b) 1.0920C, (c) 8190 C, (d) 1000 C, 13. Two balloons are filled, one with pure He gas and, the other by air, respectively. If the pressure and, temperature of these balloons are same then the, number of molecules per unit volume is:, (a) more in the He filled balloon, (b) same in both balloons, (c) more in air filled balloon, (d) in the ratio of 1 : 4, , 14. In the given (V – T) diagram, what is the relation, between pressure P1 and P2?, , (a) Cannot be predicted, , (b) P2  P1, , (c) P2  P1, (d) P2  P1, 15. A given sample of an ideal gas occupies a volume V, at a pressure P and absolute temperature T. The, mass of each molecule of the gas is m. Which of the, following gives the density of the gas?, (a) mkT, (b) P/(kT), (c) Pm/kT, (d) P/kTV, 16. At what temperature will the rms speed of oxygen, molecules become just sufficient for escaping from, the Earth’s atmosphere?, (Given: Mass of oxygen molecule(m)= 2.76 x 10-26, kg Boltzmann’s constant kB = 1.38 x 10-23 JK-1), (*data given is for atom), (a) 2.508 x 104 K (b) 8.360 x 104 K, (c) 5.016 x 104 K (d) 1.254 x 104 K, Level 1, 17. At constant pressure hydrogen is having temperature, of 3270C. Till what temperature it is to be cooled so, that the rms velocity of its molecules becomes half, of the earlier value:(a) -1230 C, (b) 1230 C, 0, (c) -100 C, (d) 00 C, 18. The speeds of 5 molecules of a gas (in ariobitary, units) are as follows 2,3,4,5,6. The root mean square, speed for these molecules is –, (a) 2.91, (b) 3.52, (c) 4.00, (d) 4.24, 19. A vessel has 6g of oxygen of pressure P and, temperature 400 K, a small hole is made in it so that, oxygen leaks out. How much oxygen leaks out if the, final pressure is P/2 and temperature is 300 K?, (a) 3g, (b) 2g (c) 4g, (d) 5g, 20. The number of oxygen molecules in a cylinder of, volume 1 m3 at a temperature of 270C and pressure, 13.8 Pa is (Boltzmaan’s constant k = 1.38 x 10-23 JK1, ) is:, (a) 6.23 x 1026, (b) 0.33 x 1028, 21, (c) 3.3 x 10, (d) None of these, 21. A cylinder contains 10 kg of gas at pressure of 107, N/m2. The quantity of gas taken out of the cylinder,, if final pressure is 2.5 x 106 N/m2, will be:, (temperature of gas is constant), (a) 15.2 kg, (b) 3.7 kg, (c) zero, (d) 7.5 kg, 22. At 100C the value of the density of a fixed mass of, an ideal gas divided by its pressure is x. At 1100C, this ratio is:(a), , 10, x, 110, , (b), , 283, x, 383

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(c) x, , (d), , 383, x, 283, , 23. The molecules of a given mass of gas have r.m.s., velocity of 200 ms-1 at 270C and 1.0 x 105 Nm-2, pressure. When the temperature and pressure of the, gas are respectively, 1270C and 0.05 x 105 Nm-2, the, r.m.s. velocity of its molecules in ms-1 is:, (a) 100 2, , (b), , 400, 3, , 100 2, 3, , (d), , 100, 3, , (c), , 24. A mixture of 2 moles of helium gas (atomic mass =, 4u), and 1 mole of argon gas (atomic mass = 40 u) is, kept at 300 K in a container. The ratio of their rms, , Vrms (helium) ,  , is close to:,  Vrms (argon) , , speeds , , (a) 2.24, (b) 0.45, (c) 0.32, (d) 3.16, 25. The temperature, at which the root mean square, velocity of hydrogen molecules equals their escape, velocity from the earth, is closest to:, [Boltzmann Constant kB = 1.38 x 10-23 J/K, Avogadro Number NA = 6.02 x 1026 /kg, Radius of Earth: 6.4 x 106 m, Gravitational acceleration on Earth = 10 ms-2], (a) 650 K, (b) 3 x 105 K, 4, (c) 10 K, (d) 800 K, 26. For a given gas at 1 atm pressure, rms speed of the, molecule is 200 m/s at 1270C. At 2 atm pressure and, at 2270C, the rms speed of the molecules will be:, (a) 80 m/s, , (b) 100 5 m / s, , (c) 80 5 m / s (d) 100 m/s, 27. The temperature at which root mean square velocity, of molecules of helium is equal to root mean square, velocity of hydrogen at N.T.P. is(a) 2730C, (b) 273 K, (c) 5460C, (d) 844 K, Kinetic energy, internal energy, degree of freedom, , Level 0, 28. The ratio of average translational kinetic energy to, rotational kinetic energy of a diatomic molecule at, temperature T is, (a) 3, (b) 7/5, (c) 5/3, (d) 3/2, 29. A gas mixture consists of 2 moles of oxygen and 4, moles of argon at temperature T. Neglecting all, vibrational modes, the total internal energy of the, system is, (a) 4 RT, (b) 15 RT, (c) 9 RT, (d) 11 RT, 30. A cylinder of 200 litre capacity is containing H2. The, total average translational kinetic energy of, molecules is 1.52 x 105 J. The pressure of H2 in the, cylinder will be in N m-2:, (a) 2 x 105, (b) 3 x 105, (c) 4 x 105, (d) 5 x 105, 31. Two monoatomic ideal gas at temperature T1 and T2, are mixed. There is no loss of energy. If the masses, of molecules of the two gases are m1 and m2 and, number of their molecules are n1 and n2 respectively., The temperature of the mixture will be:, , T1  T2, n1  n2, n T nT, (c) 2 1 1 2, n1  n2, (a), , T1 T2, , n1 n2, n T  n2T2, (d) 1 1, n1  n2, (b), , 32. Relation between the ratio of specific heats ( ) of, gas and degree of freedom ‘f’ will be, , 1 1, ,  f 2, f  2 / (  1) (d) f  2(  1), , (a)   f  2, , (b), , 1, , , , (c), 33. Gas exerts pressure on the walls of container, because the molecules –, (a) Are loosing their Kinetic energy, (b) Are getting stuck to the walls, (c) Are transferring their momentum to walls, (d) Are accelerated towards walls, 34. A gas mixture contains one mole He gas and one, mole of CO2 gas. Find the ratio of specific heat at, constant pressure that at constant volume of the, gaseous mixture:, Note :* CO2 is linear triiatomic DOF(f) same as, diatomic, (a) 2, (b) 1.5, (c) 2.5, (d) 4, 35. The ratio of the specific heats, , Cp, Cv, ,   in terms of, , degree of freedom (n) is given by:, ,  n, ,  3,  n, (c) 1  ,  2, (a) 1 , ,  2, ,  n,  1, (d) 1  ,  n, (b) 1 , , 36. A gas mixture consists of 2 moles of O2 and 4 moles, of Ar at temperature T. Neglecting all vibrational, modes, the total internal energy of the system is:-

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(a) 15 RT, (b) 9 RT, (c) 11 RT, (d) 4 RT, 37. Increase in temperature of a gas filled in a container, would lead to:, (a) increase in its mass, (b) increase in its kinetic energy, (c) decrease in its pressure, (d) decrease in intermolecular distance, ,  Cp,  Cv, , 38. The value of   , , ,  , for hydrogen, helium and, , , another ideal diatomic gas X (whose molecules are, not rigid but have an additional vibrational made),, are respectively equal to, , 7 5 9, , ,, 5 3 7, 5 7 7, , ,, (c), 3 5 5, (a), , (c) 15 RT, (d) 4 RT, 42. Two kg of a monoatomic gas is at a pressure of 4 x, 104 N/m2. The density of the gas is 8 kg/m3. What is, the order of energy of the gas due to its thermal, motion?, (a) 103 J, (b) 105 J, 6, (c) 10 J, (d) 104 J, 43. An ideal gas occupies a volume of 2m3 at a pressure, of 3 x 106 Pa. The energy of the gas is:, (a) 3 x 102, (b) 108 J, 4, (c) 6 x 10 J, (d) 9 x 106 J, 44. An HCl molecule has rotational, translational and, vibrational motions. If the rms velocity of HCl, __, , 5 7 9, , ,, 3 5 7, 5 7 7, (d) , ,, 5 3 5, , molecules in its gaseous phase is v , m is its mass, and kB is Boltzmann constant, then its temperature, will be, , (b), , Level 1, 39. The total kinetic energy of 1 mole of N2 at 270C will, be approximately:, (a) 1500 J, (b) 1500 Calories, (c) 1500 kilo Calories, (d) 1500 erg, 0, 40. 22 gm of CO2 at 27 C is mixed with 16 gm, of O2 at, 370C. The temperature of the mixture is: (At room, temperature, degree of freedom of CO2 = 7 and, degrees of freedom of O2 = 5), (a) 31.160C, (b) 270C, 0, (c) 37 C, (d) 300C, 41. The gas mixture consists of 3 moles of oxygen and 5, moles of argon at temperature T. Considering only, translational and rotational modes, the total internal, energy of the system is:, (a) 12 RT, (b) 20 RT, , __, , __, , m v2, (a), 6k B, , m v2, (b), 5k B, , __, 2, , (c), , mv, 3k B, , __, 2, , (d), , mv, 7kB, , 45. A gas is equilibrium at T kelvin. Its molecular, weight is m and its component of velocity in x, direction is vx. Then mean of its vx2 is, , 3kT, m, kT, (c), m, (a), , 3. Thermodynamics, , (b), , 2kT, m, , (d) zero

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Different thermodynamic process, , Level 0, 1. Monoatomic, diatomic and triatomic gases whose, initial volume and pressure are same, are, compressed till their volume becomes half the initial, volume., (a) If the compression is adiabatic then monoatomic, gas will have maximum final pressure., (b) If the compression is adiabatic then triatomic, gas will have maximum final pressure., (c) If the compression is adiabatic then their final, pressure will be same., (d) If the compression is isothermal then their final, pressure will be different., 2. During an adiabatic process, the pressure of a gas is, found to be proportional to the cube of its, temperature. The ratio of, , (a), , 3, 2, , (b), , 4, 3, , Cp, Cv, , (c) 2, , for the gas is:-, , (d), , 5, 3, , 3. Which of the following graphs correctly represents, the variation of   (dV/ dP) / V with P for an, ideal gas at constant temperature?, , (a) He and O2, (b) O2 and He, (c) He and Ar, (d) O2 and N2, 5. Pressure-temperature relationship for an ideal gas, undergoing adiabatic change is (  C p / Cv ), [AIPMT-92], (a) PTt = constant, (b) PT 1  constant, (c) PT t 1T t  constant, (d) P1 T   constant, 6. A quantity of air (  1.4) at 270C is compressed, suddenly, the temperature of the air system will:, (a) Fall, (b) Rise, (c) Remain unchanged, (d) First rise and then fall, 7. In thermodynamic processes which of the following, statement is not true:, (a) In an adiabatic process PV  -constant, (b) In an adiabatic process the system is insulated, from the surroundings, (c) In an isochoric process pressure remains, constant, (d) In an Isothermal process the temperature, remains constant, 8. For monoatomic gas the relation between pressure of, a gas and temperature T is P T C where C is. (For, adiabatic process), , 5, 3, 3, (c), 5, (a), , 2, 5, 5, (d), 2, (b), , 9. One mole of an ideal gas goes from an initial state A, to final state B via two processes. It first undergoes, isothermal expansion from volume V to 3V and then, its volume is reduced form 3V to V at constant, pressure. The correct P-V diagram representing the, two processes is:Ans a, 4. P.V. plots for two gases during adiabatic processes, are shown in the figure. Plots 1 and 2 should, correspond respectively to

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Ans b, 10. Conversion of water to steam is accompanied by, which process:, (a) Adiabatic, (b) Isothermal, (c) Isochoric, (d) Cyclic, 11. What is the slope for an isothermal process in PV, indicator diagram:(a), , P, V, , (a) AB and CD, (b) AB and AD, (c) AD and BC, (d) BC and CD, 15. An ideal gas mixture filled inside a balloon expands, according to the relation PV2/3 = constant. The, temperature inside the balloon is, (a) increasing, (b) decreasing, (c) constant, (d) can’t be said, 16. An ideal gas follows a process PT = constant. The, correct graph between pressure & volume is, , P, V, (d) , (b) -, , (c) Zero, 12. A monoatomic gas at a pressure P, having a volume, V expands isothermally to a volume 2V and then, adibatically to a volume 16V. The final pressure of, the gas is (take  , , 5, ), 3, , (a) 64P, , (b) 32P, , P, (c), 64, , (d) 16P, , 13. Thermodynamic processes are indicated in the, following diagram:, , Match the following, Column – I, Column – II, P., Process I, a. Adiabatic, Q. Process II, b. Isobaric, R., Process III, c. Isochoric, S., Process IV, d. Isothermal, (a) P  c, Q  a, R  d , S  b, (b) P  c, Q  d , R  b, S  a, (c) P  d , Q  b, R  a, S  c, (d) P  a, Q  c, R  d , S  b, 14. In the given graph the isothermal curves are:, , Ans c, 17. An ideal gas expands in such a way that PV2 =, constant throughout the process., (a) The graph of the process of T-V diagram is a, parabola., (b) The graph of the process of T-V diagram is a, straight line., (c) Such an expansion is possible only with heating., (d) Such an expansion is possible only with cooling., 18. Find the correct relation in given P-V diagram:, , (a) T1 = T2, (b) T1 > T2, (c) T1 < T2, (d) T1  T2, 19. In which of the following processes, heat is neither, absorbed nor released by a system?, (a) isothermal, (b) adiabatic, (c) isobaric, (d) isochoric, Level 1, 20. An ideal gas is expanding such that PT2 = constant., The coefficient of volume expansion of the gas is:, (a), , 1, T, , (b), , 2, T, , (c), , 3, T, , (d), , 4, T, , 21. During an experiment an ideal gas obeys an addition, equation of state P2V = constant. The initial, temperature and volume of gas are T and V, respectively. When it expands to volume 2V, then its, temperature will be:, (a) T, , (b), , 2T

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(c) 2 T, (d) 2 2 T, 22. Air is filled in a tube of the wheel of a car at 270C, and 2 atm pressure if the tube is suddenly bursts, the, final temp. of air will be: (   1.5,, , 23., , 24., , 25., , 26., , 21 / 3  1.251 ), , (a) -330C, (b) 00 C, 0, (c) 21.6 C, (d) 2400 C, A monoatomic gas at pressure P1 and volume V1 is, compressed adiabatically to 1/8th of original volume., What is the final pressure of the gas, (a) P1, (b) 16 P1, (c) 32 P1, (d) 64 P1, A mass of diatomic gas (  1.4) at a pressure of 2, atmospheres is compressed adiabatically so that its, temperature rises from 270C to 9270C. the pressure, of the gas in the final state is:, (a) 8 atm, (b) 28 atm, (c) 68.7 atm, (d) 256 atm, A diatomic gas undergoes adiabatic compression, and its volume reduces to half of initial volume then, its final pressure would be if gas initial pressure P, (a) 21.4 P, (b) P/2, (c) 2 P, (d) 3.07 P, A rigid diatomic ideal gas undergoes an adiabatic, process at room temperature. The relation between, temperature and volume of this process is TVx =, constant, then x is:, , 5, 3, 2, (c), 3, (a), , 2, 5, 3, (d), 5, (b), , 27. One mole of an ideal diatomic gas undergoes a, transition from A to B along a path AB as shown in, the figure. Change in internal energy of the gas, during the transition is:, , (a) -20 kJ, (c) -12 kJ, , (b) 20 J, (d) 20 kJ, , Level 0, 28. An ideal gas is taken round the cycle ABCA. In the, cycle the amount of work done involved is:-, , (a) 12 P1 V1, (b) 6 P1 V1, (c) 3 P1 V1, (d) P1 V1, 29. The volume of a gas expands by 0.25 m3 at a, constant pressure of 103 N/m2. The work done is, equal to, (a) 2.5 erg, (b) 250 J, (c) 250 W, (d) 250 N, 30. During isothermal, isobaric and adiabatic processes,, work done for same change in volume will be, maximum for:-, , (a) Isothermal, (b) Isobaric, (c) Adiabatic, (d) None of the above, 31. Calculate the work done for B  A, , Work done by gas, , 3, , 3, , (a) 6 10 J, (b) 12 10 J, 3, 3, (c) 3 10 J, (d) 4 10 J, 32. A gas is taken through the cycle A  B  C  A ,, as shown. What is the net work done by the gas?

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(a) -2000J, (b) 2000 J, (c) 1000 J, (d) Zero, 33. A thermodynamic system undergoes cyclic process, ABCDA as shown in figure. The work done by the, system in the cycle is:, , (a), (b), (c), (d), , No work is done by X, X decreases in temperature, X increases in internal energy, X doubles in pressure, , Level 1, 37. One mole of an ideal gas at temperature T1 expands, according to the law, , P,  a (constant). The work, V2, , done by the gas till temperature of gas becomes T2, is:, , 1, R(T2  T1 ), 2, 1, R(T2  T1 ), (c), 4, (a), , (a) PV, 0 0, , (b) 2PV, 0 0, , PV, 0 0, 2, , (d) Zero, , (c), , 34. A gas is compressed isothermally to half its initial, volume. The same gas is compressed separately, through an adiabatic process until its volume is, again reduced to half. Then:, (a) Compressing the gas isothermally will require, more work to be done., (b) Compressing the gas through adiabatic process, will require more work to be done., (c) Compressing the gas isothermally or, adiabatically will require the same amount of work., (d) Which of the case (whether compression, through isothermal or through adiabatic process), requires more work will depend upon the atomicity, of the gas., 35. In a cyclic process shown on the P – V diagram the, magnitude of the work done is:-, ,  P  P1 , (a)   2, ,  2 , (c), , , , 4, , 2, , (P2  P1 )(V2  V1 ), ,  V  V1 , (b)   2, ,  2 , , 2, , (d)  (P2 V2  P1V1 ), , 36. A closed container is fully insulated from outside., One half of it is filled with an ideal gas X separated, by a plate P from the other half Y which contains a, vacuum as shown in fig. When P is removed. X, moves into Y. Which of the following statement is, correct?, , 1, R(T2  T1 ), 3, 1, (d) R(T2  T1 ), 5, (b), , 38. Half mole of an ideal monoatomic gas is heated at, constant pressure of 1 atm from 200C to 900C. Work, done by gas is close to: (Gas constant R = 8.31, J/mol.K), (a) 73 J, (b) 291 J, (c) 581 J, (d) 146 J, 39. For the given cyclic process CAB as shown for a, gas, the work done is:, , (a) 1 J, (b) 5 J, (c) 10 J, (d) 30 J, 40. In an isothermal reversible expansion, if the volume, of 96gm of oxygen at270C is increased from 70 litres, to 140 litres, then work done by gas will be, (a) 300Rlog102, (b) 81R loge2, (c) 900Rlog102, (d) 2.3×900Rlog102, First law of thermodynamics

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Level 0, 41. The first law of thermodynamics is based on:(a) Law of conservation of energy, (b) Law of conservation of mechanical energy, (c) Law of conservation of gravitational p.E., (d) None of the above, 42. In a thermodynamic process pressure of a fixed mass, of a gas is changed in such a manner that the gas, release 20 joules of heat and 8 joules of work was, done on the gas. If the initial internal energy of the, gas was 30 joules, then the final internal energy will, be:, (a) 2 J, (b) 42 J, (c) 18 J, (d) 58 J, 43. When a system is taken from state ‘a’ to state ‘b’, along the path ‘acb’, it is found that a quantity of, heat Q = 200 J is absorbed by the system and a work, W = 80 J is done by it. Along the path ‘adb’, Q =, 144 J. The work done along the path ‘adb’ is, , (a) 80 J, (b) 90 J, (c) 110 J, (d) 120 J, 47. The molar specific heat under constant pressure of, oxygen is CP = 7.03 cal/mole k. The quantity of heat, required to raise the temperature from 100C to 200C, of 5 moles of oxygen under constant volume will, approximately be:, (a) 25 cal, (b) 50 cal, (c) 250 cal., (d) 500 cal., 48. A vessel contains an ideal monoatomic gas which, expands at constant pressure, when heat Q is given, to it. Then the work done in expansion is:, (a) Q, (c), , 2, Q, 5, , 49. A gas at 50 N/m2 pressure is compressed from 10m3, to 4m3 under constant pressure. Subsequently it is, given 100 J of heat. The internal energy of the gas, will be:, (a) Increased by 100 J, (b) Decreased by 200 J, (c) Increased by 400 J, (d) Increased by 200 J, 50. A system is taken along the paths A and B is shown., If the amounts of heat given in these processes are, QA and QB respectively then:, , (a) QA  QB, (a) 6J, (b) 12 J, (c) 18 J, (d) 24 J, 44. In the above question, if the work done on the, system along the curved path ‘ba’ is 52 J. heat, absorbed is, (a) -140 J, (b) -172 J, (c) 140 J (d) 172 J, 45. In question if Ua = 40 J, value of Ub will be:, (a) -50 J (b) 100 J, (c) -120 J, (d) 160 J, 46. As shown in the figure, the amount of heat absorbed, along the path ABC is 90 J and the amount of work, done by the system is 30 J. If the amount of work, done along the path ADC is 20 J the amount of heat, absorbed will be:, , 3, Q, 5, 2, (d) Q, 3, (b), , (b) QA  QB, , (c) QA  QB, (d) QA  QB, 51. If Q, E and W denote respectively the heat added,, change in internal energy and the work done in a, closed cycle process, then, (a) E = 0, (b) Q = 0, (c) W = 0, (d) Q = W = 0, 52. Gas has absorbed 2 Kcals of heat and 500 J of work, done on the gas , The internal energy change in the, system is :(a) 7900 J, (b) 8900 J, (c) 6400 J, (d) 5400 J, 53. If U and W represent the increase in internal, energy and work done by the system respectively in, a thermodynamical process, which of the following, is true?, (a) U  W , in a isothermal process, (b) U  W , in a adiabatic process, (c) U  W , in a isothermal process

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(d) U  W , in a adiabatic process, 54. During an isothermal expansion, a confined ideal, gas does +150 J of work against its surroundings., This implies that, (a) 150 J of heat has been removed from the gas, (b) 300 J of heat has been added to the gas, (c) No heat is transferred because the process is, isothermal, (d) 150 J of heat has been added to the gas, 55. An ideal gas goes from state A to state B via three, different processes as indicated in the P-V diagram, If Q1, Q2, Q3 indicate the heat absorbed by the gas, along the three processes and U1 , U 2 ,, , U 3 indicate the change in internal energy along the, three processes respectively then:, , (c) 300 J, (d) 380 J, 58. The amount of heat energy required to raise the, temperature of 1 g of Helium at constant volume,, from T1 K to T2 K is, (a), , T , 3, N a kB  2 , 4,  T1 , , (c), , 3, 3, N a k B (T2  T1 ) (d) N a k B (T2  T1 ), 2, 4, , (b), , 3, N a kB (T2  T1 ), 8, , Level 1, 59. A gas for which   5 / 3 is heated at constant, pressure., The percentage of total heat given that will be used, for external work is:, (a) 40%, (b) 30%, (c) 60% (d) 20%, 60. The volume (V) of a monoatomic gas varies with its, temperature (T), as shown in the graph. The ratio of, work done by the gas, to the heat absorbed by it,, when it undergoes a change from state A to state B, is:-, , (a) Q1  Q2  Q3 and U1  U 2  U 3, (b) Q1  Q2  Q3 and U1  U 2  U 3, (c) Q1  Q2  Q3 and U1  U 2  U 3, (d) Q3  Q2  Q1 and U1  U 2  U3, 56. One mole of an ideal diatomic gas undergoes a, transition from A to B along a path AB as shown in, the figure. Find the heat absorbed by gas during the, transition is:, , (a) -13 kJ, (b) 20 J, (c) -12 kJ, (d) N.O.T., 57. Figure below shows two paths that may be taken by, a gas to go from a state A to a state C., , 2, 5, 1, (c), 3, (a), , 2, 3, 2, (d), 7, (b), , 61. A 15g mass of nitrogen gas is enclosed in a vessel at, a temperature 270C. Amount of heat transferred to, the gas, so that rms velocity of molecules is doubled,, is about: [Take R = 8.3 J/K moles], (a) 10 kJ, (b) 0.9 kJ, (c) 6 kJ, (d) 14 kJ, 62. Following figure shows two processes A and B for a, gas. If QA and QB are the amount of heat, absorbed by the system in two cases, and U A and, , U B are changes in internal energies, respectively,, then, , (a) QA  QB ; U A  U B, (b) QA  QB ; U A  U B, (c) QA  QB ; U A  U B, In process AB, 400J of heat is added to the system, and in process BC, 100 J of heat is added to the, system. The heat absorbed by the system in the, process AC will be:, (a) 500 J, (b) 460 J, , (d) QA  QB ; U A  U B, 63. When heat Q is supplied to a diatomic gas of rigid, molecules, at constant volume its temperature, increases by DT. The heat required to produce the

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same change in temperature, at a constant pressure, is:, , 7, Q, 5, 5, (c) Q, 3, (a), , 3, Q, 2, 2, (d) Q, 3, (b), , 64. A cylinder with fixed capacity of 67.2 lit contains, helium gas at STP. The amount of heat needed to, raise the temperature of the gas by 200C is:, (a) 748 J, (b) 374 J, (c) 350 J, (d) 700 J\, 65. A sample of an ideal gas is taken through the cyclic, process abca as shown in the figure. The change in, the internal energy of the gas along the path ca is 180 J. The gas absorbs 250 J of heat along the path, ab and 60 J along the path bc. The work done by the, gas along the path abc is:, , (a) 100 J, (b) 120 J, (c) 140 J, (d) 130 J, 66. 1 g of water, of volume 1 cm3 at 1000C, is converted, into steam at same temperature under normal, atmospheric pressure (= 1 x 105 Pa). The volume of, steam formed equals 1671 cm3. If the specific latent, heat of vaporization of water is 2256 J/g, the change, in internal energy is,, (a) 2423 J, (b) 2089 J, (c) 167 J, (d) 2256 J, , Molar heat capacities, 67. When an ideal diatomic gas is heated at constant, pressure, the fraction of the heat energy supplied, which increases the internal energy of the gas is –, (a) 2/5, (b) 3/5, (c) 3/7, (d) 5/7, 68. n moles of an ideal gas with constant volume heat, capacity CV undergo an isobaric expansion by, certain volume. The ratio of the work done in the, process, to the heat supplied is:, , 4nR, Cv  nR, nR, (c), Cv  nR, (a), , nR, Cv  nR, 4nR, (d), Cv  nR, (b), , 69. a diatomic gas with rigid molecules does 10 J of, work when expanded at constant pressure. What, would be the heat energy absorbed by the gas, in this, process?, (a) 35 J, (b) 40 J, (c) 25 J, (d) 30 J, , 70. The specific heats, CP and CV of a gas of diatomic, molecules. A are given (in units of J mol-1 K-1) by 29, and 22, respectively. Another gas of diatomic, molecules, B, has the corresponding values 30 and, 21. If they are treated as ideal gases, then, (a) A has one vibrational mode and B has two, (b) Both A and B have a vibrational mode each, (c) A is rigid but B has a vibrational mode, (d) A has a vibrational mode but B has none, 71. On mixing 1 gm mole of a monoatomic with 1 gm, mole of a diatomic gas the specific heat of mixture, at constant volume will be:(a) R, (b) 3/2R, (c) 2R, (d) 5/2R, 72. Two moles of helium gas is mixed with three moles, of hydrogen molecules (taken to be rigid). What is, the molar specific heat of mixture at constant, volume? (R = 8.3 J/mol K), (a) 21.6 J/mol K (b) 19.7 J/mol K, (c) 17.4 J/mol K (d) 15.7 J/mol K, 73. For a gas CV = 4.96 cal/mole K, the increase in, internal energy of 2 mole gas in heating from 340 K, to 342 K will be:, (a) 27.80 cal, (b) 19.84 cal, (c) 13.90 Cal, (d) 9.92 cal, 74. The molar specific heats of an ideal gas at constant, pressure and volume are denoted by CP and CV,, respectively. If  , , CP, and R is the universal gas, CV, , constant, then CV is equal to:, , 1 , 1 , (  1), (d), R, , (a)  R, (c), , (b), , R, (  1), , 75. If cP and cv denote the specific heats (per unit mass), of an ideal gas of molecular weight M, then:, , R, M, R, (c) cP  cV  MR (d) cP  cV  2, M, (b) cP  cV , , (a) cP  cV  R, , Where R is the molar gas constant, 76. For a gas, , R,  0.67 . This gas is made up of, Cv, , molecules which are, (a) Diatomic, (b) Mixture of diatomic and polyatomic molecules, (c) Monoatomic, (d) Polyatomic, 77. The molar specific heat at constant pressure of an, ideal gas is (7/2)R. The ratio of specific heat at, constant pressure to that at constant volume is, (a), , 7, 5, , (b), , 8, 7, , (c), , 5, 7, , (d), , 9, 7, , Cyclic process Second Law of thermodynamics, Heat, engine, refrigerator

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Level 0, 78. In the diagram (i) to (iv) of variation of volume with, changing pressure is shown. A gas is taken along the, path ABCDA. The change in internal energy of the, gas will be:, , (a) -5J, (b) -10 J, (c) -15 J (d) -20 J, 81. A gas can be taken from A to B via two different, processes ACB and ADB. [JEE Mains-2019], When path ACB is used 60 J of heat flows into the, system and 30 J of work is done by the system. If, path ADB is used work done by the system is 10 J., The heat flow internal the system in path ADB is, , (a) 80 J, (c) 100 J, , (a) Positive in all cases (i) to (iv), (b) Positive in cases (i), (ii) and (iii) but zero in case, (iv), (c) Negative in cases (i), (ii) and (iii) but zero in, case (iv), (d) Zero in all the four cases, 79. A thermodynamic system is taken through the cycle, ABCD as shown in fig. Heat rejected by the gas, during the cycle is:, , (a), , 1, PV, 2, , (b) PV, , (c) 2 PV, (d) 4 PV, 80. An ideal gas is taken through the cycle, A  B  C  A , as shown in the figure. If the, net heat supplied to the gas in the cycle is 5J, the, work done by the gas in the process C  A is, , (b) 20 J, (d) 40 J, , 82. a carnot engine working between 300 K and 600 K, has work out put of 800 J per cycle. The amount of, heat and energy supplied to the engine from source, per cycle will be:, (a) 800 J, (b) 1600 J, (c) 1200 J, (d) 900 J, 83. the coefficient of performance of a refrigerator is 5., If the temperature inside freezer is -200C, the, temperature of the surroundings to which it rejects, heat is:, (a) 210C, (b) 310C, 0, (c) 41 C, (d) 110 C, 84. The temperature inside a refrigerator is t2 0C and the, room temperature is t1 0C. The amount of heat, delivered to the room for each joule of electrical, energy consumed ideally will be, , t1  t2, t1  273, t  273, (c) 1, t1  t2, (a), , t1, t1  t2, t  273, (d) 2, t1  t2, (b), , 85. If the system takes 100 Cal. Heat and releases 80 cal, to sink, if source temperature is 1270C find the sink, temp., (a) 470C, (b) 1270C, 0, (c) 67 C, (d) 1070C, 86. According to the second law of thermodynamics:, (a) heat energy cannot be completely converted to, work, (b) work cannot be completely converted to heat, energy, (c) for all cyclic processes we have dQ/T < 0, (d) the reason all heat engine efficiencies are less, than 100% is friction, which is unavoidable

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87. “Heat cannot be itself flow form a body at lower, temperature to a body at higher temperature” is a, statement or consequence of:, (a) second law of thermodynamics, (b) conservation of momentum, (c) conservation of mass, (d) first law of thermodynamics, Level 1, , W , 1,  of a carnot-engine is , now the temp of, 6, Q, , 88. The , , sink is reduced by 620C, then this ratio becomes, twice, therefore the initial temp of the sink and, source are respectively:, (a) 330C, 670C, (b) 370C, 990C, 0, 0, (c) 67 C, 33 C, (d) 970K, 370K, 89. A Carnot engine, whose efficiency is 40% takes in, heat from a source maintained at a temperature of, 500K. It is desired to have an engine of efficiency, 60%. Then, the intake temperature of the same, exhaust (sink) temperature must be:, (a) 750 K, (b) 600 K, , (c) Efficiency of Carnot engine cannot be made, larger than 50%, (d) 1200 K, 90. A Carnot engine, having an efficiency of  , , 1, as, 10, , heat engine, is used as a refrigerator. If the work, done on the system is 10 J, the amount of energy, absorbed from the reservoir at lower temperature is:, (a) 99 J, , (b) 90 J, , (c) 1 J, , (d) 100J, , 91. The efficiency of an ideal heat engine working, between the freezing point and boiling point of, water, is:(a) 26.8%, (b) 20%, (c) 6.25%, (d) 12.5%, 92. A Carnot engine has an efficiency of 1/6. When the, temperature of the sink is reduced by 620C, its, efficiency is doubled. The temperatures of the, source and the sink are, respectively, (a) 1240C, 620C (b) 370C, 990C, (c) 620C, 1240C, (d) 990C, 370 C, , 4. Heat Transfer, , Conduction, convection, , 1. The coefficient of thermal conductivity of copper is, nine time sthat of steel. In the composite cylindrical, bar shown in the figure what will be the temperature, at the junction of copper and steel?, , (a) 750C, (b) 670C, 0, (c) 33 C, (d) 250C, 2. Two walls of thickness d1 and d2 and thermal, conductivity k1 and k2 are in contact. In the steady, state, if the temperatures at the outer surface are T1, and T2, the temperature at the common wall is –, (a), Not more than 30 second, , K1T1d 2  k2T2 d1, K1d 2  K 2 d1, , (b), , K1T1  K 2T2, d1  d 2

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 K1d1  K 2 d 2 ,  T1T2,  T1  T2 , , (c) , , (d), , K1d1T1  K 2 d 2T2, K1d1  K 2 d 2, , 3. In natural convection, a heated portion of a liquid, moves because:, (a) Its molecular motion becomes aligned, (b) Of molecular collisions within it, (c) Its density is less than that of the surrounding, fluid, (d) Of currents of the surrounding fluid, 4. Which of the following cylindrical rods will conduct, most heat, when their ends are maintained at the, same steady temperature, (a) Length 1m; radius 1 cm, (b) Length 2m; radius 1 cm, (c) Length 2m; radius 2 cm, (d) Length 1m; radius 2 cm, 5. Consider a compound slab consisting of two, different materials having equal thickness and, thermal conductivities K and 2K, respectively. The, equivalent thermal conductivity of the slab is, (a) 3K, (c), , 2, K, 3, , (b), (d), , 4, K, 3, 2K, , 6. The material used in the manufacture of cooker must, have (K – coefficient of thermal conductivity, Sspecific heat of material used):, (a) high K and low S, (b) low K and low S, (c) high K and high S, (d) low K and high S, 7. Two conductors having thickness d1 and d2 thermal, conductivity k1 and k2 are placed one above the, another. Find the equivalent thermal conductance:-, , (d1  d 2 )(k1d 2  k 2d1 ), (a), 2(k1  k 2 ), (d  d )(k d  k 2d1 ), (b) 1 2 1 2, 2(k1  k 2 ), k k (d  d ), (c) 1 2 1 2, (d) None of these, d1k2  d 2 k1, , 8. A cylindrical rod having temperature T1 and T2 at its, ends. The rate of flow of heat is Q1 cal/sec. If all the, dimensions are doubled keeping T1 and T2 constant,, then rate of flow of heat Q2 will be:, (a) 4Q1, (b) 2Q1, (c) Q1 / 4, (d) Q1 / 2, 9. Consider the rods of same length of different, specific heats (s1,s2) conductivities (k1, k2) and area, of cross-sections (A1, A2) and both having, temperature T1 and T2 at their ends. If the rate of loss, of heat due to conduction is equal, then:, (a) k1 A1  k2 A2, (c) k2 A1  k1 A2, , k1 A1 k2 A2, , s1, s2, kA kA, (d) 1 1  1 2, s2, s1, (b), , 10. 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 ./  2l0 (b) r  2r0 , /  l0, (c) r  r0 ./  2l0 (d) r  r0 ./  l0, Level 1, 11. Three rods made of the same material and having the, same cross-section have been joined as shown in the, fig. Each rods is of the same length. The left and, right ends are kept at 00C and 900C respectively. The, temperature of the junction of the three rods will be, , (a) 450C, (b) 600C, 0, (c) 30 C, (d) 200C, 12. 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 1000C and that of copper at 00C, the, temperature of interface is, (a) 800, (b) 200C, 0, (c) 60 C, (d) 400 C, 13. A cylindrical metallic rod in thermal contact with, two reservoirs of heat at its two ends conducts an, amount of heat Q in time t. The metallic rod is, melted and the materials formed into a rod of half, the radius of the original rod. What is the amount of, heat conducted by the new rod, when placed in, thermal contact with the reservoirs in time t?, , Q, 2, Q, (c), 16, (a), , (b), , Q, 4, , (d) 2Q, , Effect of heat transfer, 14. A slab of stone of area 0.36 m2 and thickness 0.1 m, is exposed on the lower surface to steam at 1000C. A, block of ice at 00C rests on the upper surface of the, slab. In one hour 4.8 kg of ice is melted. The thermal, conductivity of slab is:, (Given latent heat of fusion of ice = 3.36 x 105 J kg1, ), (a) 2.05 J/m/s/0C (b) 1.02 J/m/s/0C, (c) 1.24 J/m/s/0C (d) 1.29 J/m/s/0C, 15. A cylinder of radius R is surrounded by a cylindrical, shell of inner radius R and outer radius 2R. The, thermal conductivity of the material of the inner, cylinder is K1 and that of the outer cylinder is K2., Assuming no loss of heat, the effective thermal, conductivity of the system for heat flowing along the, length of the cylinder is: [JEE Mains 2019], (a) K1  K 2, (c), , 2 K1  3K 2, 5, , K1  K 2, 2, K1  3K 2, (d), 4, (b)

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16. Temperature difference of 1200C is maintained, between two ends of a uniform rod AB of length 2L., Another bent rod PQ, of same crossection as AB and, length, , 3L, , is connected across AB (see fig.) In, 2, , steady state, temperature difference between P and, Q will be close to:, , (a) 600C, (b) 750C, 0, (c) 35 C, (d) 450C, 17. Two materials having coefficients of thermal, conductivity ‘3K’ and ‘K’ and thickness ‘d’ and, ‘3d’, respectively, are joined to form a slab as shown, in the fig. The temperatures of the outer surfaces are, ‘  2 ’ and ‘ 1 ’ respectively, (  2  1 ). The, temperature at the interface is, , (a), ,  2  1, , (c), , 1, 3, , 2, , , 2 2, 3, , 9 2, 10 10,  5, (d) 1  2, 6, 6, (b), , 1, , , , 18. A heat source at T = 103 K is connected to another, heat reservoir at T = 102 K by a copper slab which is, 1 m thick. Given that the thermal conductivity of, copper is 0.1 WK-1 m-1, the energy flux through it in, the steady state is:, (a) 90 Wm-2, (b) 200 Wm-2, -2, (c) 65 Wm, (d) 120 Wm-2, Radiation, , Level0, 19. Radius of two spheres of same material are 1 & 4 m, respectively and their temp. are 4 x 103 and 2 x 103, K respectively. Then ratio of emitted energy of, sphere per sec. will be:, (a) 1:2, (b) 2:1, (c) 1:1, (d) 4:1, , 20. If temp. of ideal black body increased by 10% what, will be % increase in quantity of radiation emitted, from it’s surface, (a) 10% (b) 40% (c) 46%, (d) 100%, 21. If a carved black utensil is heated to high, temperature and then brought in dark then, (a) Both utensil and its carving will shine, (b) Only carving will shine, (c) Only utensil will shine, (d) None of the utensil and carving will shine, 22. The original temperature of a black body is 7270C., Calculate temperature at which this black body total, radiant energy, become double, (a) 971 K, (b) 1190 K, (c) 2001 K, (d) 1458 K, 23. The ideal black body is:, (a) Hot coat at high temperature, (b) Surface of glass printed with coal tank, (c) Metal surface, (d) A hollow container painted with black colour, 24. The energy emitted per second by a black body at, 270C is 10 J. If the temperature of the black body is, increased to 3270C, the energy emitted per second, will be:, (a) 20 J, (b) 40J, (c) 80J, (d) 160 J, 25. Two spherical bodies A(radius 6 cm) and B(radius, 18 cm) are at temperature T1 and T2 respectively., The maximum intensity in the emission spectrum of, A is at 500 nm and in that of B is at 1500 nm., Considering them to be black bodies, what will be, the ratio of the rate of total energy radiated by A to, that of B?, (a) 9, (b) 6, (c) 12 (d) 3, 26. A black body is at 7270C. It emits energy at a rate, which is proportional to:, (a) (727)4, (b) (727)2, (c) (1000)4, (d) (1000)2, 0, 27. A black body at 227 C radiates heat at the rate of 7, Cals/cm2s. At a temperature of 7270C, the rate of, heat radiated in the same units will be:, (a) 60, (b) 50, (c) 112, (d) 80, 28. Suppose the sun expands so that its radius becomes, 100 times its present radius and its surface, temperature becomes half of its present value. The, total energy emitted by it then will increase by a, factor of:, (a) 104(b) 625, (c) 256, (d) 16, 29. 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:, (a) 450, (b) 1000, (c) 1800, (d) 225, 30. We consider the radiation emitted by the human, body. Which of the following statements is true:, (a) The radiation emitted is in the infra-red region, (b) The radiation is emitted only during the day

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(c) The radiation is emitted during the summers and, absorbed during the winters, (d) The radiation emitted lies in the ultraviolet, region and hence is not visible., Level 1, 31. The total radiant energy per unit area, normal to the, direction of incidence, received at a distance R from, the centre of a star of radius r, whose outer surface, radiates as a black body at a temperature T K is, given by:, , 4 2T 4, (a), R2,  r 2T 4, (c), 4 R 2, , (b), ,  r 2T 4, , R2,  r 4T 4, (d), R4, , 32. Assuming the sun to have a spherical outer surface, of radius r, radiating like a black body at, temperature t0C, the power received by a unit, surface, (normal to the incident rays) at distance R, from the centre of the Sun is:, , r 2 (t  273)4, 4 r 2 t 2, (b), R2, R2, r 2 (t  273)4, 16 2 r 2 t 4, (c), (d), R2, 4 R 2, (a), , 33. Three objects coloured black, gray and white can, withstand hostile conditions upto 28000C. These, objects are thrown into a furnace where each of them, attains a temperature of 20000C. Which object will, glow brightest:, (a) The white object, (b) The black object, (c) All glow with equal brightness, (d) Gray object, 34. Cooling rate of a sphere of 600 K at external, environment (200 K) is R when the temperature of, sphere is reduced to 400 K then cooling rate of the, sphere is, (a), , 3, 16, 9, R (b), R (c), R, 16, 3, 27, , (d) None, , Weins displacement law, 35. A piece of iron is heated in a flame. It first becomes, dull red then becomes reddish yellow and finally, turns to white hot. The correct explanation for the, above observation is possible by using:, (a) Wien’s displacement Law, (b) Kirchoff’s Law, (c) Newton’s Law of cooling, (d) Stefan’s Law, 36. Star S1 emits maximum radiation of wavelength 420, nm and the star S2 emits maximum radiation of, wavelength 560 nm, what is the ratio of the, temperature of S1 and S2:, (a) 4/3, (b) (4/3)1/4, (c) ¾, (d) (3/4)1/2, , 37. The Wien’s displacement law express relation, between, (a) Wavelength corresponding to maximum energy, and temperature, (b) radiation energy and wavelength, (c) Temperature and wavelength, (d) Colour of light and temperature, 38. If m denotes the wavelength at which the radiative, emission from a black body at a temperature T K is, maximum then:, (a) mT, (b) mT 2, (c) m T 1, (d) m T 2, 39. A black body at 200 K is found to emit maximum, energy at a wavelength 14  m . When its, temperature is raised to 1000K, then wavelength at, which maximum energy emitted is:, (a) 14  m, (b) 15  m, (c) 2.8  m, (d) 28  m, 40. If the radius of a star is R and it acts as a black body,, what would be the temperature of the star, in which, the rate of energy production is Q?, (a) (4 R 2 Q/  )1/4, (b) (Q/ 4 R 2  )1/4, (c) Q / 4 R 2, , (d) (Q/ 4 R 2 )1/2, , 41. A black body is at a temperature of 5760 K. The, energy of radiation emitted by the body at, wavelength 250 nm is U1, at wavelength 500 nm is, U2 and that at 1000 nm is U3. Wien’s constant, b =, 2.88 x 106 nmK. Which of the following is correct?, (a) U1  0 (b) U 3  0 (c) U1  U 2 (d) U 2  U1, 42. The power radiated by a black body is P and it, radiates maximum energy at wavelength 0 . If the, temperature of the black body is now charged so that, it radiates maximum energy at wavelength, , 3, 0 , the, 4, , power radiated by it becomes nP. The value of n is:(a), , 3, 4, , (b), , 4, 256, (c), 3, 81, , (d), , 81, 256, , Newton’s Law of cooling, , Level 0, 43. A bucket full of hot water cools from 750C to 700C, in time T1, from 700 to 650C in time T2 and from, 650C to 600C in time T3 then

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(a) T1  T2  T3, , (b) T1  T2  T3, , (c) T1  T2  T3, (d) T1  T2  T3, 44. A body takes T minutes to cool from 620C to 610.C, when the surrounding temperature is 300C. The time, taken by the body to cool from 460C to 45.50C is:, (a) Greater than T minutes, (b) Equal to T minutes, (c) Less than T minutes, (d) Equal to T/2 minutes, 45. Certain quantity of water cools from 700C to 600C in, the first 5 minutes and to 540C in the next 5 minutes., The temperature of the surroundings is, (a) 420 C, (b) 100 C, (c) 450 C, (d) 200 C, 46. A body cools from a temperature 3T to 2T in 10, minutes. The room temperature is T. Assume that, Newton’s law of cooling is applicable. The, temperature of the body at the end of next 10, minutes will be, (a) T, , (b), , 7, 3, T (c), T, 4, 2, , (d), , 4, T, 3, , 47. An object kept in a large room having air, temperature of 250C takes 12 minutes to cool from, 800C to 700C. The time taken to cool for the same, object from 700C to 600C would be nearby, (a) 10 min, (b) 12 min, (c) 20 min, (d) 15 min, 48. A cup of tea cools from 800C to 600C in one minute., The ambient temperature is 300C. In cooling from, 600C to 500C. It will take:, (a) 50 sec, (b) 90 sec, (c) 60 sec, (d) 48 sec, 49. A liquid in a beaker has temperature  (t) at time t, and  0 is temperature of surroundings, then, according to Newton’s law of cooling the correct, graph between logc (  0 ) and t is:, , Ans c, …by Praveen Gupta