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Class 11 Physics Objective Chapter – 12 Thermodynamics
1. An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62°C, its efficiency is doubled. Temperature of the source is:
( a ) 124°C
( b ) 37°C
( c ) 62°C
( d ) 99°C
Ans:-( d )
2. Internal energy of a perfect gas is
( a ) wholly potential energy
( b ) wholly kinetic energy
( c ) partially K.E. and partially P.E. of the molecules
( d ) difference of K.E. and P.E. of the molecules
Ans:-( a )
3.The branch of physics which deals with the concepts of heat and temperature and the inter conversion of heat and other forms of energy is called as
( a ) Statistical mechanics
( b ) Thermodynamics
( c ) Fluid dynamics
( d ) Classical physics
Ans:-( b )
4.The process forbidden by the first law of thermodynamics is
( a ) conversion of work into heat.
( b ) conversion of heat into work.
( c ) change in internal energy.
( d ) none of the above.
Ans:-( d )
5. A thermodynamical system is changed from state ( P1, V1 )to ( P2, V2 )by two different processes, the quantity which will remain same is:
( a ) ΔQ
( b ) ΔW
( c ) ΔQ + ΔW
( d ) ΔQ – ΔW
Ans:-( d )
6. A sample of 0.1 g of water at 100°C and normal pressure ( 1.013 × 105 N m–2 )requires 54 cal of heat energy to convert to steam at 100°C. If the volume of the steam produced is 167.1 cc, the change in internal energy of the sample, is
( a ) 104.3 J
( b ) 208.7 J
( c ) 42.2 J
( d ) 84.5 J
Ans:-( b )
7. First law of thermodynamics states that
( a ) heat is a form of energy
( b ) system has pressure
( c ) system has temperature
( d ) system can do work
Ans:-( a )
8.The Zeroth law leads to the concept of
( a ) temperature
( b ) heat
( c ) internal energy
( d ) work
Ans:-( a)
9. The temperatures of inside and outside of a refrigerator are 273 K and 303 K respectively. Assuming, that the refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surrounding will be nearly:
( a ) 10 J
( b ) 20 J
( c ) 30 J
( d ) 50 J
Ans:-( c )
10.In an isothermal process, the internal energy of the system
( a ) decreases
( b ) increases
( c ) does not change
( d ) none of the above
Ans:-( c)
11. Thermodynamics is the ____ science
( a ) Microscopic
( b ) Macroscopic
( c ) Both a and b
( d ) None
Ans:-( b )
12. At a given volume and temperature, the pressure of a gas
( a ) varies inversely as its mass
( b ) varies inversely as the square of its mass
( c ) varies linearly as its mass
( d ) is independent of its mass
Ans:-( c )
13. A black body at a temperature of 227°C radiates heat at the rate of 20 cal m-2s-1. When its temperature rises to 727°C, the heat radiated will be
( a ) 40 units
( b ) 160 units
( c ) 320 units
( d ) 640 units
Ans:-( c )
14.The internal energy change in a system that has absorbed 2 kcal of heat and done 500 J of work is
( a ) 6400 J
( b ) 5400 J
( c ) 7900 J
( d ) 8900 J
Ans:-( c )
15. A system X is neither in thermal equilibrium with Y nor with Z. The systems Y and Z
( a ) may be in thermal equilibrium
( b ) None of these
( c ) cannot be in thermal equilibrium
( d ) must be in thermal equilibrium
Ans:-( a )
16. Which of the following is incorrect regarding the first law of thermodynamics? A. It is not applicable to any cyclic process B. It is a restatement of the principle of conservation of energy C. It introduces the concept of the internal energy D. It introduces the concept of the entropy
( a ) A and D
( b ) B and C
( c ) C and A
( d ) A and B
Ans:-( a)
17.Thermodynamics is concerned with the
( a ) change of state
( b ) measurement of heat
( c ) transfer of heat
( d ) none of the above
Ans:-( c)
18. Pressure, volume, temperature, mass are the
( a ) Microscopic variables
( b ) Macroscopic variables
( c ) Intensive variables
( d ) Extensive variables
Ans:-( b )
19. During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature. The ratio Cp/Cv for the gas is
( a ) 2
( b ) 3/2
( c ) 4/3
( d ) 5/3
Ans:-( b )
20. In a thermodynamic process, pressure of a fixed mass of the gas is changed in such a manner that the gas molecules give out 30 J of heat. Also, 10 J of work is done on the gas. If the internal energy of the gas was 40 J, what will be the final internal energy?
( a ) 20 J
( b ) -20 J
( c ) 80 J
( d ) zero
Ans:-( a)
21.110 joule of heat is added to a gaseous system whose internal energy is 40 J, then the amount of external work done is
( a ) 150 J
( b ) 70 J
( c ) 110 J
( d ) 40 J
Ans:-( b )
22. Which of the following macroscopic variable is not measurable?
( a ) None of these
( b ) Volume
( c ) Pressure
( d ) Mass
Ans:-( a )
23.The translational kinetic energy of gas molecules at temperature T for one mole of a gas is
( a ) ( 3/2 )RT
( b ) ( 9/2 )RT
( c ) ( 1/3 )RT
( d ) ( 5/2 )RT
Ans:-( a)
24. For an adiabatic process
( a ) temperature changes are bound to occur.
( b ) perfect thermal insulation with surroundings are required.
( c ) process should be quick.
( d ) all of the above are correct
Ans:-( d )
25. Two systems in thermal equilibrium with a third system separately are in thermal equilibrium with each other, this is the statement of
( a ) First law of thermodynamics
( b ) Second law of thermodynamics
( c ) Zeroth law of thermodynamics
( d ) None
Ans:-( c )
26.The temperature of a gas is due to the
( a ) K.E. of the gas molecules.
( b ) repulsive force between the molecules.
( c ) attractive force between the molecules.
( d ) P.E. of the gas molecules.
Ans:-( a)
27. Which of the following parameters dose not characterize the thermodynamic state of matter?
( a ) work
( b ) volume
( c ) pressure
( d ) Temperature
Ans:-( a )
28.First law of thermodynamics is consequence of conservation of
( a ) work
( b ) energy
( c ) heat
( d ) all of these
Ans:-( b )
29. Which of the following is a state variable ?
( a ) Internal energy
( b ) Heat
( c ) Work
( d ) All of these
Ans:-( a )
30. A Carnots engine works as a refrigerator between 250 K and 300 K. If it receives 750 calories of heat from the reservoir at the lower temperature, the amount of heat rejected at the higher temperature is
( a ) 900 cal
( b ) 625 cal
( c ) 750 cal
( d ) 1000 cal
Ans:-( a )
31. For an isothermal expansion
( a ) process should be performed in very small steps.
( b ) perfect conducting communication with the surroundings is required.
( c ) process should be slow.
( d ) all of the above are correct.
Ans:-( d )
32.The SI unit of specific heat capacity is
( a )J kg-1 K
( b )J kg K
( c )J kg-1 K-1
( d )None
Ans:-( c)
33.The temperature of reservoir of Carnots engine operating with an efficiency of 70% is 1000 kelvin. The temperature of its sink is
( a ) 300 K
( b ) 400 K
( c ) 500 K
( d ) 700 K
Ans:-( a )
34.In a thermodynamic process, pressure of a fixed mass of the gas is changed in such a manner that the gas molecules give out 30 J of heat. Also, 10 J of work is done on the gas. If the internal energy of the gas was 40 J, what will be the final internal energy?
( a ) 20 J
( b ) −20 J
( c ) 80 J
( d ) zero
Ans:-( a )
35. If cp and cv denote the specific heats per unit mass of an ideal gas of molecular weight M, then
( a ) cp – cv = R/M2
( b ) cp – cv = R
( c ) cp – cv = R/M
( d ) cp – cv = MR
Ans:-( c )
36.The internal energy of an ideal gas depends upon
( a ) temperature
( b ) specific volume
( c ) pressure
( d ) density
Ans:-( a )
37.The temperatures of inside and outside of a refrigerator are 273 K and 303 K respectively. Assuming, that the refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surrounding will be nearly
( a )10 J
( b )20 J
( c )30 J
( d )50 J
Ans:-( c )
38. In a Carnot’s engine, at the end point of the cycle, the temperature is
( a ) less than the initial temperature.
( b ) more than the initial temperature.
( c ) equal to the initial temperature.
( d ) zero.
Ans:-( c )
39.The amount of heat required to raise the temperature of 1g of water by 1°C is called as
( a )1 joule
( b )1 kJ
( c )One calorie
( d )None
Ans:-( c )
40. Heat cannot by itself flow from a body at lower temperature to a body at higher temperature is a statement as a conseqence of
( a ) conservation of mass
( b ) conservation of momentum
( c ) first law of thermodynamics
( d ) second law of thermodynamics
Ans:-( d )
41. A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of source be increased, so as to increase its efficiency by 50% of original efficiency?
( a ) 275 K
( b ) 325 K
( c ) 250 K
( d ) 380 K
Ans:-( c )
42. If the ratio of specific heat of a gas at constant pressure to that at constant volume is g, the change in internal energy of a mass of gas, when the volume changes from V to 2V at constant pressure P, is
( a ) PV /( γ – 1)
( b ) PV
( c ) R /( γ – 1)
( d ) γPV /( γ – 1)
Ans:-( a )
43.Energy transfer brought about by moving the piston of a cylinder containing the gas is known as
( a ) work
( b ) heat
( c ) pressure
( d ) temperature
Ans:-( a )
44.In a thermodynamic process, pressure of a fixed mass of the gas is changed in such a manner that the gas molecules give out 30 J of heat. Also, 10 J of work is done on the gas. If the internal energy of the gas was 40 J, what will be the final internal energy
( a ) 20 J
( b ) −20 J
( c ) 80 J
( d ) zero
Ans:-( a )
45. The first law of thermodynamics is represented as
( a ) dQ = dU + dW
( b ) dQ = 2dU + dW
( c ) dQ = dU – dW
( d ) dQ = dU + 2dW
Ans:-( a )
46. The variables which describes equilibrium states of system are called as
( a ) Intensive variables
( b ) Extensive variables
( c ) State variables
( d ) Thermodynamic state variables
Ans:-( d )
47. Which of the following is a state variable
( a ) Internal energy
( b ) Heat
( c ) Work
( d ) All of these
Ans:-( a )
48. For a diatomic gas change in internal energy for a unit change in temperature for constant pressure and constant volume is U1 and U2 respectively. What is the ratio of U1 and U2 ?
( a ) 5 : 3
( b ) 3 : 5
( c ) 1 : 1
( d ) 5 : 7
Ans:-( c )
49. One mole of an ideal gas requires 207 J heat to rise the temperature by 10 K when heated at constant pressure. If the same gas is heated at constant volume to raise the temperature by the same 10 K, the heat required is ( Given the gas constant R = 8.3 J/mole K )
( a ) 198.7 J
( b ) 29 J
( c ) 215.3 J
( d ) 124 J
Ans:-( d )
50. The state of a thermodynamic system is represented by
( a ) pressure, volume and temperature
( b ) volume only
( c ) pressure only
( d ) number of moles
Ans:-( a )
51.A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of source be increased, so as to increase its efficiency by 50% of original efficiency?
( a ) 275 K
( b ) 325 K
( c ) 250 K
( d ) 380 K
Ans:-( c)
52.The efficiency of a Carnot engine working between 227°C and 27°C is
( a ) 100%
( b ) 50%
( c ) 40%
( a ) 20%
Ans:-( c )
