Quiznetik

Thermodynamics | Set 1

1. Which of the following cycle is less efficient as compared to the remaining?

Correct : E. Otto cycle

2. The number of degrees of freedom in case of triatomic gases is

Correct : C. 6

3. At critical point the enthalpy of vaporisation is

Correct : B. Zero

4. In which of the following case the process of sublimation can occur?

Correct : B. Solid carbondioxide

5. Work done in a free expansion process is

Correct : D. Zero

6. If a system neither exchange mass nor energy with the surroundings, it is known as

Correct : B. Isolated system

7. Food can be cooked quicker in a pressure cooker because

Correct : C. Steam remains within the cooker

8. A surface which diffusely reflects and emits tha same amount of energy which it receives by radiation, is known as

Correct : D. A perfect radiating surface

9. Exhaust gases from a engine possess

Correct : E. Kinetic energy

10. Which one of the following is an indirect reaction device?

Correct : D. Propeller

11. Cetane number of a diesel fuel is a measure of its

Correct : E. ignition quality

12. A thermistor is a

Correct : D. Miniature resistance

13. Which of the following is a reversible process?

Correct : A. Extension and compression of a spring

14. Power required for the engine is

Correct : C. 9.23 kW

15. According to Charle's law

Correct : A. At constant pressure the volume of a gas is proportional to its temperature

16. The mean free path of a gas least depends on

Correct : A. volume of gas

17. The value of universal gas constant in S.I. units is

Correct : B. 8314 J/kg mole/?k

18. Which of the following valve is installed between the boiler and the feed pump?

Correct : E. Feed check valve

19. Thermodynamic equilibrium is completely defined by the specifications of

Correct : D. All the above together

20. A gas (inversion temperature Ti) undergoing Joule Thomson expansion at temperature T will produce cooling effect only when

Correct : B. Ti > T

21. During an adiabatic expansion, the increase in volume is associated with

Correct : C. Decrease in pressure and decrease in temperature

22. The mean free path of a gas molecule increases with

Correct : C. increase in temperature

23. In a Carnot cycle the heat is rejected at

Correct : B. Constant temperature

24. Which of the following statement is incorrect?

Correct : D. Latent heat per kg of steam decreases as the pressure of steam increases

25. Non-dimensional numbers generally involved in case of heat transfer from horizontal cylinders by natural convection are

Correct : E. (B), (C) and (D) above

26. Which of the following is the best fuel for diesel engines?

Correct : E. Paraffins

27. Air leaking from a punctured tube is an example of

Correct : A. Throttling

28. The percentage of carbondioxide in the exhaust gases from a diesel engine cannot exceed

Correct : C. 29%

29. Internal energy of a perfect gas depends on

Correct : E. Temperature only

30. The process during which external work done is not zero, is

Correct : B. Constant pressure process

31. Which of the following cycle consists of two isothermal and constant volume processes?

Correct : E. Ericsson cycle

32. A perfect black body is

Correct : A. One which absorbs all radiant energy at all wavelengths

33. The characteristics of a control volume are

Correct : D. The volume, shape and position with respect to an observer are fixed

34. By doubling the temperature the radiant heat will increase

Correct : A. 16 times

35. Which of the following is not a property of the system

Correct : D. Heat

36. The mixture formation in a carburettor is based on the principle of

Correct : A. Venturi principle

37. Heating wet steam at constant temperature is same as heating at

Correct : A. Constant pressure

38. A liquid flowing through a tube is turbulent. In which case will the maximum change in heat transfer coefficient occur?

Correct : A. Diameter of the tube is increased 4 time maintaining the ratio of liquid flow constant

39. All of the following cycles consists of two isothermal processes EXCEPT

Correct : C. Brayton cycle

40. Which of the following introduces irreversibility in the actual Carnot engine operation?

Correct : B. Losses from working fluid in transit

41. Which of the following is the best fuel for S.I. engines?

Correct : C. Aromatics

42. The cycle generally used for gas turbines is

Correct : A. Brayton cycle

43. The slope of constant pressure line on temperature entropy diagrm is given by

Correct : B. T/Cp

44. In automobiles clutch is mounted between

Correct : E. Flywheel and gear box

45. During an adiabatic process the change in entropy is

Correct : B. Zero

46. The behaviour of which of the following vapour is closer to that of a gas?

Correct : D. Superheated vapour

47. The ratio of the rise in temperature of a gas when compressed adiabatically to that when compressed isothermally to the same extent is

Correct : E. More than 1

48. In all irreversible processes, the entropy of the system

Correct : A. Increases

49. Which of the following remains constant during an adiabatic process?

Correct : C. entropy

50. Reduced pressure is

Correct : A. dimensionless

51. In the polytropic process equation pvn = constant, if the value of n is infinitely large the process is termed as

Correct : B. Constant volume

52. The ratio of the rise in temperature of a gas when compressed adiabatically to that when compressed isothermally to the same extent is

Correct : A. More than 1

53. Other factors remaining constant, if the temperature of sink is increased, the efficiency of the Carnot engine will

Correct : E. decrease

54. One of the most efficient engines ever developed operates between 2100 k and 700 k. Its actual efficiency is 40%. What percentage of its maximum possible efficiency is this?

Correct : C. 60%

55. For any reversible process, the change in entropy of the system and surroundings is

Correct : B. Zero

56. If all the variables of a steam are in-dependent of time it is said to be in

Correct : C. Steady flow

57. Entropy of mixing is always

Correct : A. positive

58. A system comprising a single phase is called a

Correct : D. Homogeneous system

59. An open system

Correct : D. Has a mass transfer across its boundaries, and the mass within the system is not necessarily constant

60. In the regenerative cycle

Correct : E. Part of the steam is withdrawn from the turbine and is used in heating the feed water

61. Which of the following is a path function quantity?

Correct : A. Work done

62. An ordinary mercury thermometer can be used for temperatures about

Correct : C. 300?C

63. Triple point

Correct : D. Is that point where three phases solid, liquid and gas exist together

64. The characteristics of a control volume are

Correct : E. There is material flow across the boundary

65. The gas turbine works on

Correct : B. Brayton cycle

66. All of the following are intensive properties EXCEPT

Correct : B. Mass

67. A body of weight 100 N falls freely through a distance of 10 m against an atmospheric drag force of 5 N. Considering the body as the system, the work interaction is

Correct : D. 50 Nm

68. In a steam turbine when steam expands, the entropy

Correct : B. Does not change

69. Of the following first law statements, choose the one that is wrong

Correct : C. the heat transfer cannot exceed the work done

70. If the dryness fraction of a sample by throttling calorimeter is 0.8 and that by separating calorimeter is also 0.8, then the actual dryness fraction of sample will be taken as

Correct : E. 0.64

71. Work done by an expanding gas under adiabatic condition results in

Correct : A. Temperature decrease

72. Carburetted water gas is obtained by

Correct : E. Passing alternately steam and air through while hot carbon

73. A process which does not dissipate available energy is known as

Correct : D. Ideal process

74. The weight of 1 cu-m of carbon dioxide at NTP if the characteristic gas constant is 19.28 kg metre/kg/?C, would be

Correct : C. 1.962 kg

75. The ability of gasoline to resist detonation during combustion is given by

Correct : E. Octane number

76. "The internal energy of a gas is a function of temperature". Which of the following name is associated with the above law?

Correct : E. Joule

77. The solubility of a gas in a liquid at small concentration is represented by

Correct : C. Henry's law

78. A scavenging pump is used in

Correct : C. two stroke spark ignition engines

79. The difference between two specific heats of a gas is equal to universal constant when

Correct : B. 1 gm molecule of gas is heated

80. Which of the following is a non-petroleum fuel?

Correct : D. Alcohol

81. The average pressure on the walls of a vessel will be doubled if the

Correct : B. the number of molecules in the vessel is doubled

82. The fastest moving gas molecules are those of

Correct : C. Hydrogen

83. which of the following set of quantities contains intensive variables?

Correct : E. Pressure, temperature and density

84. A system

Correct : A. Is a specified region, not necessarily of constant volume, where transfer of energy and/or mass are to be studied

85. Transformer oil having kinematic viscosity of 3.66 x 10-6 m2/s flows through a tube 8 mm diameter at velocity of 0.6 m/s. The value of Reynolds number of flow would be

Correct : E. 1310

86. An isentropic process is always

Correct : D. Reversible and adiabatic

87. In a reversible polytropic process

Correct : A. The entropy remains constant

88. A gas which obeys kinetic theory perfectly is known as

Correct : B. Perfect gas

89. An automobile heats up while lying in a parking 10 ton a sunny day. The process can be assumed to be

Correct : C. isobaric

90. The efficiency of a Carnot engine is given as 0.75. If the cycle direction is reversed, what will be the value of COP of reversed Carnot cycle

Correct : A. 0.33

91. Which rays have the least wavelength?

Correct : D. Cosmic rays

92. The difference between two specific heats of a gas is equal to universal gas constant

Correct : C. When 1 gm molecule heated

93. 1 cu-m of steam having dryness franction 0.85 at 12 ata mixes with 1.5 kg of water at 12?C at constant pressure. The dryness fraction of resulting steam would be

Correct : D. 0.637

94. In centrifugal compressors, the ratio of outlet whirl velocity to blade velocity at outlet is known as

Correct : B. Slip factor

95. In case of centrifugal compressors the phenomenon of unsteady, periodic and reversed flow is known as

Correct : A. Surging

96. A Rankine cycle working with saturated steam differs thermodynamically from a Carnot cycle only in the fact that

Correct : D. Heat is supplied to the water at temperatures below the maximum temperature of the cycle

97. In case of ideal triatomic gas, the ratio of specific heats Cp/Cv would be

Correct : B. 1.33

98. During adiabatic expansion which of the following remains constant

Correct : C. Entropy

99. Which of the following is a boiler accessory?

Correct : B. Economiser

100. Draught ensures supply of

Correct : A. Air for combustion