Quiznetik

Internal Combustion Engines (I.C. Engines) | Set 1

1. Advantage of reciprocating IC engines over steam turbine is

Correct : D. all of the above

2. The intake charge in a diesel engine consists of

Correct : A. air alone

3. Engines of different cylinder dimensions, power and speed can be compared on the basis of

Correct : C. mean effective pressure

4. Disadvantages of reciprocating IC engine are

Correct : D. all of the above

5. Gudgeon pin forms the link between

Correct : B. piston and small end of connecting rod

6. In a four-stroke IC engine cam shaft rotates at

Correct : C. halt the speed of crankshaft

7. Thermal efficiency of CI engine is higher than that of SI engine due

Correct : B. higher compression ratio

8. SI engines are of

Correct : D. all of the above

9. Compression ratio in diesel engines is of the order of

Correct : D. 14-20

10. Main advantage of a two-stroke engine over four-stroke engine is

Correct : D. all of the above

11. Engines used for ships are normally

Correct : B. two-stroke CI engines of very high power

12. If L is the stroke and N is the rpm, mean piston speed of two-stroke engine

Correct : C. 2LN

13. The volumetric efficiency of the SI engine is comparatively

Correct : A. lower than CI engine

14. Brake specific fuel consumption is defined as

Correct : D. fuel consumption per brake power hour

15. Engine can be fired with

Correct : D. any of the above fuels

16. A two-stroke engine can be identified by

Correct : C. absence of valves

17. Advantage of two-stroke engine is

Correct : D. all of the above

18. Charge pressure at the inlet port of a two-stroke engine is

Correct : D. higher than atmospheric

19. The most perfect method of scavenging is

Correct : B. uniflow scavenging

20. Two-stroke SI engines suffer from

Correct : A. fuel loss

21. At the same speed two-stroke engine of the same size as a four-stroke engine will develop

Correct : C. twice the power

22. Two wheelers without deflector type piston use

Correct : D. cross scavenging

23. Crankcase scavenged engines have delivery ratio of

Correct : C. equal to 1

24. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

Correct : C. 2

25. In a diesel engine, the fuel is ignited by

Correct : C. heat resulting from compressing air that is supplied for combustion

26. Scavenging air in diesel engine means

Correct : D. air used for forcing burnt gases out of engine's cylinder during the exhaust period

27. Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged?

Correct : B. no

28. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called

Correct : C. relative efficiency

29. Compression ratio of LC. Engines is

Correct : A. the ratio of volumes of air in cylinder before compression stroke and after compression stroke

30. A perfect engine works on the Carnot cycle between 727 °C and 227°C. The efficiency of the engine is

Correct : A. 0.5

31. The air standard Otto cycle consists of

Correct : A. two constant volume and two isentropic processes

32. In air standard Diesel cycle at fixed r and fixed n

Correct : B. ƞthermal decreases with increase in heat addition and cut-off ratio

33. Mean effective pressure of Otto cycle is

Correct : B. directly proportional to pressure ratio

34. For a given compression ratio the work output of Otto cycle is

Correct : A. increases with Increase in r

35. For a given value of r, efficiency of Otto cycle

Correct : B. increases with compression ratio

36. For dual combustion cycle for fixed value of heat addition and compression ratio

Correct : A. mep wil be greater with increase in rp, and decrease in rc

37. The normal range of, compression ratio for Otto cycle is

Correct : A. 6 to 10

38. The normal range of compression ratio for Diesel cycle is

Correct : C. 15 to 20

39. For the same compression ratio and heat addition

Correct : C. ƞOtto> ƞDual > ƞDiesel

40. for the same compression ratio and heat rejection,

Correct : A. ƞOtto> ƞDual > ƞDiesel

41. When the engines are built to withstand the sane thermal and mechanical stresses

Correct : A. ƞDiesel > ƞDual > ƞOtto

42. For the same peak pressure and heat input

Correct : C. ƞDiesel > ƞDual > ƞOtto

43. For the same peak pressure and work output

Correct : D. ƞDiesel > ƞDual > ƞOtto

44. Brayton cycle is used in

Correct : B. gas turbines

45. The actual efficiency of a good engine is about _______of the estimated fuel-air cycle efficiency.

Correct : B. 85%

46. With dissociation peak temperature is obtained

Correct : C. when the mixture is slightly rich

47. With dissociation the exhaust gas temperature

Correct : A. decreases

48. Fuel-air ratio affects maximum power output of the engine due to

Correct : C. both (a) and (b)

49. Mean effective pressure at a given compression ratio is maximum when the air-fuel ratio is

Correct : B. lower than stoichiometric

50. For a compressor process with variable specific heat the peak temperature and pressure are _______compared to constant specific heat

Correct : A. lower

51. Dissociation can be considered as

Correct : D. all of the above

52. Time loss factor in actual cycle is due to

Correct : A. Progressive combustion

53. The major loss in a SI engine is due to

Correct : D. variation in specific heat and chemical equilibrium

54. Fuel-air cycle efficiency is less than air-standard cycle efficiency by an amount equal to

Correct : C. loss due to specific heat variation and chemical equilibrium

55. The major loss in a CI engine is

Correct : B. loss due to incomplete combustion

56. The ratio of the actual efficiency and the fuel-air cycle efficiency for CI engines is about

Correct : D. 0.6-0.8

57. In an actual SI engine the pumping loss with respect to speed

Correct : B. Increases

58. The volumetric efficiency is affected by

Correct : D. all of the above

59. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is

Correct : C. more

60. In a typical medium speed, 4-stroke cycle diesel engine

Correct : A. fuel injection starts at 10° before to dead center and ends at 20° after tor dead center

61. The amount of heat liberated by complete combustion of unit quantity of fuel is known as ________

Correct : C. Calorific value

62. The calorific value of gaseous fuels is expressed in terms of

Correct : D. D. kcal/m3

63. What is the significance of calorific value?

Correct : A. Helps in deciding which fuel is good

64. Which gas has the highest calorific value among given option?

Correct : C. Hydrogen

65. Which calorimeter is used to find calorific values of solid and liquid fuels?

Correct : B. Bomb calorimeter

66. Which calorimeter is used to find calorific values of gaseous fuels?

Correct : B. Junker calorimeter

67. What is the factor on which, difference between the two heating values of fuel depends on?

Correct : C. Chemical composition

68. The Bomb calorimeter is used to determine the calorific value of:

Correct : A. solids and liquid fuels

69. If the intake air temperature of I.C. engine increases, its efficiency will

Correct : B. decrease

70. All heat engines utilize

Correct : A. low heat value of oil

71. An engine indicator is used to determine the following

Correct : D. m.e.p. and I.H.P.

72. Fuel oil consumption guarantees for I .C. engine are usually based on

Correct : B. high heat value of oil

73. Combustion in compression ignition engines is

Correct : B. heterogeneous

74. The air requirement of a petrol engine during starting compared to theoretical required for complete combustion is

Correct : B. loss

75. Diesel fuel, compared to petrol is

Correct : C. more difficult to ignite

76. When crude oil is heated, then which of the following hydrocarbon is given off first.

Correct : D. natural gas.

77. The rating of a diesel engine, with increase in air-intlet temperature, will

Correct : B. decrease linearly

78. A 75 cc engine has following parameter as 75 cc

Correct : C. swept volume

79. A heat engine utilises the

Correct : C. high heat value of oil

80. Gaseous-fuel guarantees are based on

Correct : B. low heat value of oil

81. Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads

Correct : C. the small difference in cooling water temperature or in internal friction has a disproportionate effect

82. Polymerisation is a chemical process in which molecules of a compound become

Correct : A. larger

83. Which of the following is the lightest and most volatile liquid fuel

Correct : D. gasoline

84. The theoretically correct air fuel ratio for petrol engine is of the order of

Correct : D. 15 : 1

85. Air fuel ratio for idling speed of a petrol engine is approximately

Correct : C. 10:1

86. Air fuel ratio at which a petrol engine can not work is

Correct : D. 20 : 1 and less

87. Advantage of gaseous fuel is that

Correct : B. it can mix easily with air

88. Paraffins are in general represented by

Correct : C. CnH2n+2

89. Paraffins have molecular structure of

Correct : A. chain saturated

90. Olefins are represented by the formula

Correct : A. CnH2n

91. Hydrocarbons are decomposed into smaller hydrocarbons by

Correct : C. cracking

92. The molecular structure of the straight-run gasoline is changed by

Correct : B. reforming

93. For SI engines fuels most preferred are

Correct : A. aromatics

94. For CI engine fuels most preferred are

Correct : B. paraffins

95. Octane number of iso-octane is

Correct : D. 100

96. Ignition quality of diesel fuel is indicated by its

Correct : B. cetane number

97. Flash point of fuel oil is

Correct : A. minimum temperature to which1 oil is heated in order to give off inflammable vapours in Sufficient quantity to ignite momentarily when brought in contact with a flame

98. Gasohol is a mixture of

Correct : B. 10% ethanol +90% gasoline

99. Stoichiometric air-fuel ratio of petrol is roughly

Correct : C. 15:1

100. Venturi in the carburetor results in

Correct : B. increase of air velocity