Interview Questions on IC Engines

1. What happens to efficiency when the temperature of intake air in internal combustion engine increases
  1. Remain same
  2. Decrease
  3. Increase
  4. None of these

Answer:B

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2. When additional air under pressure is forced into the cylinder of engine then that process is called
  1. Scavenging
  2. Turbulence
  3. Supercharging
  4. Pre-ignition

Answer:C

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3. What does the mean effective pressure obtained from engine indicator specifies
  1. Maximum pressure developed
  2. Minimum pressure
  3. Instantaneous pressure at any instant
  4. Average pressure

Answer:D

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4. The compression ratio in petrol engines is kept low as compared to diesel engines because higher compression ratio in petrol engines would lead to pre-ignition of fuel.
  1. Disagree
  2. Agree

Answer:B

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5. Pour point of fuel oil is the
  1. Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
  2. Temperature at which it solidifies or congeals
  3. It catches fire without external aid
  4. Indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off

Answer:B

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6. The maximum temperature in the I.C. engine cylinder is of the order of
  1. 500-1000°C
  2. 1000-1500°C
  3. 1500-2000°C
  4. 2000-2500°C

Answer:D

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7. In compression ignition engines, swirl denotes a
  1. Random motion of the gases in the combustion chamber
  2. Random motion of the gases in the combustion chamber
  3. Outward motion of the gases in the combustion chamber
  4. None of the above

Answer:B

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8.What does an engine indicator show
  1. Speed
  2. Temperature
  3. Volume of cylinder
  4. m.e.p. and I.H.P.

Answer:D

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9. The engines in which the combustion of fuel takes place inside the engine cylinder are called internal combustion engines.
  1. False
  2. True

Answer:B

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10. A diesel engine has
  1. one valve
  2. two valves
  3. three valves
  4. four valves

Answer:C

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11. The diesel engines are also known as __________ engines
  1. compression ignition
  2. spark ignition

Answer:A

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12. The purpose of testing an internal combustion engine is
  1. to get the information, which can’t be obtained through calculations
  2. to conform the data used in design, the validity of which may be doubtful
  3. to please the car owner about the performance of the engine
  4. all of the above

Answer:D

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13. In a four stroke cycle petrol engine, the charge is ignited at
  1. 30° before top dead centre
  2. 30° after top dead centre
  3. 30° before bottom dead centre
  4. 30° after bottom dead centre

Answer:A

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14. The relative efficiency of an I.C. engine is the ratio of the indicated thermal efficiency to the air standard efficiency.
  1. Incorrect
  2. Correct

Answer:B

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15. In a four stroke cycle petrol engine, the charge is compressed when both the valves (i.e. inlet valve and exit valve) are closed
  1. Agree
  2. Disagree

Answer:A

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16. The scavenging efficiency of a four stroke cycle diesel engine is
  1. below 50%
  2. between 50 and 85%
  3. between 85 and 95%
  4. between 95 and 100%

Answer:D

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17. The combustion in compression ignition engines is
  1. heterogeneous
  2. homogeneous
  3. both (a) and (b)
  4. none of these

Answer:A

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18. The increase of efficiency of a compression ignition engine, as the load decreases, is due to
  1. higher maximum temperature
  2. qualitative governing
  3. quantitative governing
  4. hit and miss governing

Answer:B

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19. The injection pressure in a diesel engine is about
  1. 10 bar
  2. 100 bar
  3. 150 bar
  4. 500 bar

Answer:B

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20.Is it correct to say that in hit & miss governing the fuel supply is cut off completely during 1 or more no. of cycles
  1. Yes
  2. No

Answer:A

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21. The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
  1. 25%
  2. 50%
  3. 70%
  4. 100%

Answer:B

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22. The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is known as
  1. mechanical efficiency
  2. overall efficiency
  3. volumetric efficiency
  4. relative efficiency

Answer:C

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23.The exhaust valve in a four stroke cycle petrol engine
  1. opens at 50° before BDC (bottom dead centre) and closes at 15° after TDC (top dead centre)
  2. opens at BDC (bottom dead centre) and closes at TDC (top dead centre)
  3. may open and close anywhere
  4. None of the above

Answer:A

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24. Which of the following does not relate to a spark ignition engine ?
  1. Ignition coil
  2. Spark plug
  3. Carburettor
  4. Fuel injector

Answer:D

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25. The brake power of a diesel engine, keeping other parameters constant, can be increased by
  1. decreasing the density of intake air
  2. increasing the temperature of intake air
  3. increasing the pressure of intake air
  4. decreasing the pressure of intake air

Answer:C

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26. Lubrication in I.C. engines dissipates the heat generated from the moving parts due to friction.
  1. True
  2. False

Answer:A

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27. In diesel engines, the fuel is injected in the form of very fine spray, into the engine cylinder, which gets ignited due to high temperature of the compressed air
  1. Agree
  2. Disagree

Answer:A

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28. Pre-ignition is caused by the spontantaneous combustion of the mixture before the end of the compression stroke, and is due to
  1. cylinder walls being too hot
  2. overheated spark plug points
  3. red hot carbon deposits on cylinder walls
  4. any one of these

Answer:D

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29. The expansion of fuel in a four stroke cycle diesel engine
  1. begins at 15° before TDC (top dead centre) and ends at 30° after TDC (top dead centre)
  2. begins at TDC (top dead centre) and ends at 30° after TDC (top dead centre)
  3. begins at 15° after TDC (top dead centre) and ends at 30° before BDC (bottom dead centre)
  4. may start and end anywhere

Answer:C

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30. The object of supercharging the engine is
  1. to reduce mass of the engine per brake power
  2. to reduce space occupied by the engine
  3. to increase the power output of an engine when more power is needed
  4. all of the above

Answer:D

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31. The correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines is
  1. four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine
  2. four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine
  3. four stroke C.I. engine, two stroke S.I. engine, four stroke S.I. engine
  4. two stroke S.I. engine, four stroke S.I. engine, four stroke C.I. engine

Answer:A

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32. In the diesel engines, the turbulent effect of fuel mixture occurs in an open combustion chamber due to the shape/ layout of the piston crown, the inlet port and the valve
  1. True
  2. False

Answer:A

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33. In a diesel engine, the duration between the time of injection and ignition, is known as
  1. pre-ignition period
  2. delay period
  3. period of ignition
  4. burning period

Answer:B

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34. The detonating tendency in petrol engines increases with increase of compression ratio.
  1. True
  2. False

Answer:A

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35. In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will __________ the knocking tendency.
  1. not effect
  2. decrease
  3. increase

Answer:C

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36. The reference fuels for knock rating of spark ignition engines would include
  1. iso-octane and alpha-methyl naphthalene
  2. normal octane and aniline
  3. iso-octane and normal hexane
  4. normal heptane and iso-octane

Answer:D

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37.The thermal efficiency of diesel engines is about
  1. 15%
  2. 30%
  3. 50%
  4. 70%

Answer:D

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38. The self ignition temperature of petrol is __________ as compared to diesel oil.
  1. same
  2. lower
  3. higher

Answer:C

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39. The pressure inside the cylinder is __________ the atmospheric pressure during the exhaust stroke.
  1. equal to
  2. Below
  3. Above

Answer:C

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40. In an SI Engine the pre -ignition happens before the spark is produced whereas detonation develops after the spark is produced
  1. Agree
  2. Disagree

Answer:A

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41. The basic requirement of a good combustion chamber is
  1. minimum turbulence
  2. low compression ratio
  3. high thermal efficiency and power output
  4. low volumetric efficiency

Answer:C

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42. The thermal efficiency of diesel engines on weak mixtures is
  1. Unaffected
  2. Lower
  3. Higher
  4. dependent on other factors

Answer:C

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43. What is the cetan no. of alpha-methyl-naphthalene (C11 H10)
  1. 0
  2. 50
  3. 100
  4. 120

Answer:A

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44. High speed compression engines operate on
  1. Otto cycle
  2. Diesel cycle
  3. all of theseDual-combustion cycle
  4. all of these

Answer:C

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45. In a four stroke cycle petrol engine, the inlet valve
  1. opens at TDC (top dead centre) and closes at BDC (bottom dead centre)
  2. opens at 20° before TDC (top dead centre) and closes at 40° after BDC (bottom dead centre)
  3. opens at 20° after TDC (top dead centre) and closes at 20° before BDC (bottom dead centre)
  4. may open or close anywhere

Answer:B

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46. The higher combustion chamber wall temperature in compression ignition engines will __________ knocking tendency.
  1. increase
  2. reduce
  3. not effect

Answer:B

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47. A two stroke cycle engine gives __________ mechanical efficiency than a four stroke cycle engine.
  1. Higher
  2. Higher

Answer:A

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48. The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
  1. not effect
  2. decrease
  3. increase

Answer:C

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49. The ratio of the heat equivalent to one kW hour to the heat in fuel per B.P. hour is termed as brake thermal efficiency.
  1. Yes
  2. No

Answer:A

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50. The theoretically correct mixture of air and petrol is
  1. 10:1
  2. 15:1
  3. 20:1
  4. 25:1

Answer:B

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51. In qualitative governing, the quantity of fuel is varied to suit the load on the engine and the total charge of air is altered.
  1. Correct
  2. Incorrect

Answer:B

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52. The function of a distributor in a coil ignition system of I.C. engines is
  1. to distribute spark
  2. to distribute power
  3. to distribute current
  4. to time the spark

Answer:B

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53. The frictional power (F.P.) is given by
  1. F.P. = B.P. - I.P.
  2. F.P. = I.P. - B.P.
  3. F.P. = B.P./I.P.
  4. F.P. = I.P./B.P.

Answer:C

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54. The knocking tendency in spark ignition engines can be decreased by adding dopes like tetra ethyle lead and ethylene dibromide.
  1. Agree
  2. Disagree

Answer:A

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55. A diesel engine has compression ratio from
  1. 6 to 10
  2. 10 to 15
  3. 15 to 25
  4. 25 to 40

Answer:C

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56. A petrol engine, during suction stroke draws
  1. air only
  2. petrol only
  3. a mixture of petrol and air

Answer:C

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57. A carburettor is used to supply
  1. petrol, air and lubricating oil
  2. air and diesel
  3. petrol and lubricating oil
  4. petrol and air

Answer:D

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58. A supercharged engine as compared to an ordinary engine
  1. requires smaller foundation
  2. is lighter
  3. consumes less lubricating oil
  4. all of these

Answer:D

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59. Which of the following statement is correct regarding petrol engines?
  1. The ignition of fuel and air happens due to heat of compression at high pressure.
  2. The ignition of fuel and required amount of air ie the fuel-air mixture happens with the help of a spark plug
  3. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition.
  4. all of the above

Answer:B

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60. Supercharging __________ the power developed by the engine
  1. has no effect on
  2. Increases
  3. Decreases

Answer:B

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61. The colour of exhaust from diesel engine is generally
  1. white
  2. bluish
  3. black
  4. violent

Answer:C

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62. In compression ignition engines, swirl denotes a
  1. haphazard motion of the gases in the chamber
  2. rotary motion of the gases in the chamber
  3. radial motion of the gases in the chamber
  4. none of the above

Answer:B

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63. The delay period in compression ignition engines depends upon
  1. the temperature & pressure present in the cylinder at the time of injection
  2. nature of the fuel mixture strength
  3. relative velocity between the fuel injection & air turbulence pressure of residual gases
  4. all of the above

Answer:D

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64. A mixture containing 65% of iso-octane and 35% of normal heptane will have
  1. cetane number 65
  2. octane number 65
  3. qetane number 35
  4. octane number 35

Answer:B

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65. The thermal efficiency of petrol and gas engines is about
  1. 15%
  2. 30%
  3. 50%
  4. 70%

Answer:B

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66. Which of the following statement is wrong?
  1. To remove knocking in the C.I. engines, we need to attain auto-ignition not early and need a long delay period.
  2. As the fuel, in C.I. engines, is injected at the end of compression stroke, so there will be no pre-ignition.
  3. In compression ignition engines, because of hetrogeneous mixture, the rate of pressure rise is comparatively lower.
  4. None of the above

Answer:A

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67. What is used to ensure that air and petrol are mixed in required proportion and supplied to engine druing suction stroke.
  1. fuel pump
  2. Injector
  3. Carburettor
  4. none of these

Answer:C

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68. The advancing of spark timing in spark ignition engines will __________ knocking tendency
  1. increase
  2. Reduce
  3. not effect

Answer:A

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69. The ratio of the brake power to the indicated power is called
  1. mechanical efficiency
  2. overall efficiency
  3. indicated thermal efficiency
  4. volumetric efficiency

Answer:A

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70. A turbo-jet does not require a turbine to drive the compressor.
  1. True
  2. False

Answer:B

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71. For the same maximum pressure and heat input, the exhaust temperature of petrol engine is __________ than that of diesel engine.
  1. Less
  2. more

Answer:B

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72. What is the cetane number of straight chain paraffin like C16H34
  1. 0
  2. 50
  3. 100
  4. 120

Answer:C

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73. Morse test is used to determine the I.P. of a
  1. single cylinder petrol engine
  2. four stroke engine
  3. single cylinder diesel engine
  4. multi-cylinder engine

Answer:D

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74. In a four stroke cycle diesel engine, the exhaust valve
  1. opens at 30° before bottom dead cnetre and closes at 10° after top dead centre
  2. opens at 30° after BDC (bottom dead centre) and closes at 10° before TDC (top dead centre)
  3. opens at BDC (bottom dead centre) and closes at TDC (top dead centre)
  4. may open and close anywhere

Answer:A

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75. The maximum propulsive efficiency of a turbo-jet engine is at a speed of
  1. 1000 km/h
  2. 2000 km/h
  3. 2400 km/h
  4. 3000 km/h

Answer:C

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76. The two stroke cycle engines have lighter flywheel
  1. Agree
  2. Disagree

Answer:A

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77. The thermodynamic cycle on which the petrol engine works, is
  1. Otto cycle
  2. Joule cycle
  3. Rankine cycle
  4. Stirling cycle

Answer:A

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78. Which of the following does not relate to a compression ignition engine?
  1. Fuel pump
  2. Fuel injector
  3. Governor
  4. Carburettor

Answer:D

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79. The correct mixture strength (by weight) for petrol is about
  1. 14.6:1
  2. 18.5:1
  3. 20.4:1
  4. 22.6:1

Answer:A

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80. The working pressure and temperature inside the cylinder of an internal combustion engine is __________ as compared to a steam engine.
  1. Low
  2. very low
  3. high
  4. very high

Answer:D

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81. The voltage required to produce a spark across the gap, between the sparking points is
  1. 2000 to 4000 volts
  2. 4000 to 6000 volts
  3. 6000 to 10 000 volts
  4. 10 000 to 12 000 volts

Answer:C

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82. If the speed of the engine is increased, the indicated power will
  1. Increase
  2. Decrease
  3. remain same

Answer:A

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83. The petrol engines are also known as __________ engines.
  1. compression ignition
  2. spark ignition

Answer:B

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84. The specific fuel consumption per B.P. hour for a petrol engine is about
  1. 0.2 kg
  2. 0.25 kg
  3. 0.3 kg
  4. 0.35 kg

Answer:B

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85. In order to eliminate knocking in compression ignition engines, there should be
  1. short delay period
  2. late auto-ignition
  3. low compression ratio
  4. high self ignition temperature of fuel

Answer:A

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86. In a petrol engine, the charge is ignited with the help of a spark plug.
  1. yes
  2. No

Answer:A

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87. Number of working strokes per minute in a 2-stroke cycle engine are __________ the speed of the engine in rpm.
  1. equal to
  2. one-half
  3. Twice
  4. four-times

Answer:A

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88. The injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to
  1. inject fuel in combustion chamber at the end of compression stroke
  2. inject fuel at a high velocity to enable atomisation
  3. ensure that penetration is not high
  4. all of the above

Answer:D

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89. A two stroke cycle engine occupies larger floor area than a four stroke cycle engine
  1. Yes
  2. No

Answer:B

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90. The indicated M.E.P. (mean effective pressure) of an engine is derived from the indicator diagram drawn with the assistance of an engine indicator.
  1. True
  2. False

Answer:A

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91. Theoretically, a four stroke cycle engine should develop __________ power as that of a two stroke cycle engine.
  1. Half
  2. Same
  3. Double
  4. four times

Answer:A

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92. A fuel of cetane number 40 has the same ignition quality as a mixture of
  1. 40% cetane and 60% alpha methyl naphthalene
  2. 40% alpha methyl napthalene and 60% cetane
  3. 40% petrol and 60% diesel
  4. 40% diesel and 60% petrol

Answer:A

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93. The two reference fuels used for cetane rating are
  1. cetane and iso-octane
  2. cetane and alpha-methyl naphthalene
  3. cetane and normal heptane
  4. cetane and tetra ethyl lead

Answer:B

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94. In petrol engines, the delay period is of the order of
  1. 0.001 second
  2. 0.002 second
  3. 0.003 second
  4. 0.004 second

Answer:B

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95. In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.
  1. equal to
  2. Below
  3. Above

Answer:B

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96. A diesel engine is __________ as compared to petrol engine, both running at rated load
  1. equally efficient
  2. less efficient
  3. more efficient

Answer:C

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97. Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine ?
  1. inlet valve closing after bottom dead centre
  2. inlet valve closing before bottom dead centre
  3. inlet valve opening before top dead centre
  4. exhaust valve closing after top dead centre

Answer:B

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98. The pressure at the end of compression, in petrol engines, is approximately
  1. 10 bar/li>
  2. 20 bar
  3. 25 bar
  4. 35 bar

Answer:A

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99. The sparking in a petrol engine increases pressure and temperature of the products of combustion, but the volume remains constant.
  1. Yes
  2. No

Answer:A

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100. Which of the following statement is wrong ?
  1. A four stroke cycle engine develops twice the power as that of a two stroke cycle engine.
  2. For identical power developed, a 4-stroke cycle engine is lighter, less bulkier and requires less floor area.
  3. The petrol engines are costly than diesel engines.
  4. all of the above

Answer:D

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101. The turbine of the turbo-prop engine is __________ that of the turbo-jet engine.
  1. same as
  2. smaller than
  3. bigger than

Answer:C

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102. A higher compression ratio causes
  1. pre-ignition
  2. increase in detonation
  3. an acceleration in the rate of combustion
  4. any one of these

Answer:D

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103. Which statement(s) out of given below options is correct
  1. The compression ratio in a petrol engines varies from 6 to 10.
  2. Higher the compression ratio in diesel engine, higher would be the pressure
  3. Petrol engines work on Otto cycle.
  4. all of the above

Answer:D

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104. A fuel will detonate less if it has higher self ignition temperature.
  1. True
  2. False

Answer:A

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105. Which of the following fuel detonates readily ?
  1. Benzene
  2. Iso-octane
  3. Normal heptane
  4. Alcohol

Answer:C

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106. The running cost of a petrol engine is __________ than that of a diesel engine
  1. higher
  2. lower

Answer:A

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107. In a petrol engine, if diesel is used, then the engine will
  1. not run
  2. run more efficiently
  3. run at high speed
  4. explode

Answer:A

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108. The knocking tendency in spark ignition engines may be decreased by
  1. controlling the air-fuel mixture
  2. controlling the ignition timing
  3. controlling the exhaust temperature
  4. reducing the compression ratio

Answer:D

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109. In a two stroke engine, the working cycle is completed in two revolutions of the crankshaft.
  1. Correct
  2. Incorrect

Answer:B

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110. In a petrol engine, the mixture has the lowest pressure at the
  1. beginning of suction stroke
  2. end of suction stroke
  3. end of compression stroke
  4. none of these

Answer:B

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111. The increase in intake temperature of internal combustion engines will __________ efficiency.
  1. have no effect on
  2. increase
  3. decrease

Answer:C

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112. The indicated power for multi-cylinder engine will be same as that of a single cylinder engine.
  1. True
  2. False

Answer:B

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113. In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have
  1. low density
  2. low temperature
  3. long ignition delay
  4. all of these

Answer:D

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114. A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. What would be the volume of air-fuel mixture per stroke (given vol. efficiency= 0.88; mechanical efficiency=0.90
  1. 248 cm3
  2. 252 cm3
  3. 264 cm3
  4. 286 cm3

Answer:C

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115. The purpose of a supercharger is to take air from the atmosphere surrounding the engine, compresses it to a higher pressure and finally put it into the inlet valve of the engine
  1. Correct
  2. Incorrect

Answer:A

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116. Iso-octane (C8H18) has octane number of
  1. 0
  2. 50
  3. 100
  4. 120

Answer:C

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117. An ignition coil in the spark ignition engines supplies __________ voltage to the spark plug
  1. High
  2. Low

Answer:A

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118. The operation of forcing additional air under pressure into the engine cylinder is known as
  1. supercharging
  2. carburation
  3. Turbulence
  4. delay period

Answer:A

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119. The cylinder of a gas engine is made __________ than that of the petrol engine.
  1. Smaller
  2. Larger

Answer:B

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120. The thermal efficiency of a petrol engine is __________ as compared to diesel engine.
  1. Same
  2. Less
  3. More

Answer:B

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121. The compression ignition engines are governed by
  1. hit and miss governing
  2. qualitative governing
  3. quantitative governing
  4. combination of (b) and (c

Answer:b

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122. The delay period in oil engines increases with increase in the speed of engine.
  1. Agree
  2. Disagree

Answer:B

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123. The inlet valve of a four stroke cycle internal combustion engine remains open for
  1. 130°
  2. 180°
  3. 230°
  4. 270°

Answer:C

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124. The brake power is always greater than indicated power
  1. Agree
  2. Disagree

Answer:B

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125. A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of
  1. 75% iso-octane and 25% normal heptane
  2. 75% normal heptane and 25% iso-octane
  3. 75% petrol and 25% diesel
  4. 75% diesel and 25% petrol

Answer:A

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126. A two stroke cycle engine gives __________ the number of power strokes as compared to the four stroke cycle engine, at the same engine speed.
  1. Half
  2. Same
  3. Double
  4. four times

Answer:C

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127. By higher octane number of spark ignition fuel, it is meant that the fuel has
  1. higher heating value
  2. higher flash point
  3. lower volatility
  4. longer ignition delay

Answer:D

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128. The spark ignition engines are governed by
  1. hit and miss governing
  2. qualitative governing
  3. quantitative governing
  4. combination of (b) and (c)

Answer:C

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129. If petrol is used in a diesel engine, then
  1. low power will be produced
  2. efficiency will be low
  3. higher knocking will occur
  4. black smoke will be produced

Answer:C

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130. If the temperature of intake air in internal combustion engine increases, then its efficiency will
  1. remain same
  2. Decrease
  3. Increase

Answer:B

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131. In a coil ignition system of petrol engines, a condenser is connected across the contact-breaker in order to
  1. prevent sparking across the gap between the points
  2. have rapid break of the primary current in order to provide a higher voltage in the secondary circuit
  3. both (a) and (b)
  4. none of the above

Answer:C

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132. In a four stroke cycle petrol engine, the expansion
  1. starts at top dead centre and ends at bottom dead centre
  2. begins at 30° before TDC (top dead centre) and ends at 50° before BDC (bottom dead centre)
  3. begins at 30° after TDC (top dead centre) and ends at 50° after BDC (bottom dead centre)
  4. may start and end anywhere

Answer:B

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133. As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
  1. increase maximum pressure and maximum temperature
  2. reduce maximum pressure and maximum temperature
  3. increase maximum pressure and decrease maximum temperature
  4. decrease maximum pressure and increase maximum temperature

Answer:B

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134. The __________ engines can work on very lean mixture of fuel.
  1. spark ignition
  2. compression ignition

Answer:B

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135. The ignition quality of petrol is expressed by
  1. cetane number
  2. octane number
  3. calorific value
  4. all of these

Answer:B

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136. In petrol engines, advancing of the spark timing will __________ the knocking tendency
  1. not effect
  2. Decrease
  3. Increase

Answer:C

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137. Which of the following statement is correct regarding normal cetane?
  1. It is a regular fuel used for knock rating of diesel engines.
  2. Its chemical name is normal-hexadecane.
  3. It has long carbon chain structure
  4. all of the above

Answer:D

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138. The knocking tendency in compression ignition engines for a given fuel will be
  1. enhanced by decreasing compression ratio
  2. enhanced by increasing compression ratio
  3. dependent on other factors
  4. none of the above

Answer:A

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139. In a four stroke cycle engine, the sequence of operations
  1. suction, compression, expansion and exhaust
  2. suction, expansion, compression and exhaust
  3. expansion, compression, suction and exhaust
  4. compression, expansion, suction and exhaust

Answer:A

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140. A diesel engine, during suction stroke, draws
  1. air only
  2. diesel only
  3. a mixture of diesel and air

Answer:A

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141. Anti-knock for compression ignition engines is
  1. Napthene
  2. tetra ethyl lead
  3. amyl nitrate
  4. Hexadecane

Answer:C

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142. In petrol engines, using a fixed octane rating fuel, the increase in compression ratio will not effect the knocking tendency
  1. Agree
  2. Disagree

Answer:B

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143. Supercharging is the process of supplying the intake air to the engine cylinder at a density __________ the density of the surrounding atmosphere.
  1. equal to
  2. less than
  3. greater than

Answer:C

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144. The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
  1. Morse test
  2. prony brake test
  3. motoring test
  4. heat balance test

Answer:A

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145. Stoichiometric ratio is
  1. chemically correct air-fuel ratio by weight
  2. chemically correct air-fuel ratio by volume
  3. actual air-fuel ratio for maximum efficiency
  4. none of the above

Answer:B

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146. In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
  1. fuel pump
  2. fuel injector
  3. spark plug
  4. none of these

Answer:C

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147. The cetane number of diesel oil, generally available, is
  1. 20 to 25
  2. 25 to 30
  3. 30 to 40
  4. 40 to 55

Answer:D

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148. The octane number of petrol, generally available, is
  1. 20 to 40
  2. 40 to 60
  3. 60 to 80
  4. 80 to 100

Answer:D

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149. Morse test can be conducted for
  1. petrol engines
  2. diesel engines
  3. multi-cylinder engines
  4. all of these

Answer:C

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150. the object of providing masked inlet valve in the air passage of compression ignition engines is to
  1. enhance flow rate
  2. control air flow
  3. induce primary swirl
  4. induce secondary turbulence

Answer:C

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151. In an internal combustion engine, the process of removing the burnt gases from the combustion chamber of the engine cylinder is known as
  1. Scavenging
  2. Detonation
  3. Supercharging
  4. Polymerisation

Answer:A

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152. The overall efficiency is defined as the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time
  1. True
  2. False

Answer:A

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153. During suction stroke of a four stroke petrol engine, the inlet valve opens and the charge is sucked into the cylinder as the piston moves upwards from the bottom dead centre.
  1. True
  2. False

Answer:B

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154. In diesel engines, the ignition takes place due to the heat produced in the engine cylinder at the end of compression.
  1. Correct
  2. Incorrect

Answer:A

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155. The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called
  1. mechanical efficiency
  2. overall efficiency
  3. indicated thermal efficiency
  4. volumetric efficiency

Answer:B

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156. A petrol engine has compression ratio from
  1. 6 to 10
  2. 10 to 15
  3. 15 to 25
  4. 25 to 40

Answer:A

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157. In petrol engines, using a fixed octane rating fuel, the increase in engine speed will decrease the knocking tendency
  1. Yes
  2. No

Answer:A

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158. The power actually developed by the engine cylinder of an I.C. engine is known as
  1. theoretical power
  2. actual power
  3. indicated power
  4. none of these

Answer:C

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159. The ignition of the charge by some hot surface within the engine before the passage of spark is called
  1. pre-ignition
  2. Detonation
  3. ignition delay
  4. auto-ignition

Answer:A

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160. The ratio of the indicated thermal efficiency to the air standard efficiency is known as
  1. mechanical efficiency
  2. overall efficiency
  3. volumetric efficiency
  4. relative efficiency

Answer:D

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161. The normal heptane (C7H16) is given a rating of __________ octane number
  1. 0
  2. 50
  3. 100
  4. 120

Answer:A

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162. A diesel engine has inlet valve, fuel injection valve and exhaust valve.
  1. Yes
  2. No

Answer:A

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163. The knocking in diesel engines may be prevented by
  1. reducing the delay period
  2. raising the compression ratio
  3. increasing the inlet pressure of air
  4. all of these

Answer:D

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164. The loud pulsating noise heard within the cylinder of an internal combustion engine is known as
  1. Detonation
  2. Turbulence
  3. pre-ignition
  4. supercharging

Answer:A

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165. The air-fuel ratio of the petrol engine is controlled by
  1. Carburettor
  2. Injector
  3. Governor
  4. none of these

Answer:A

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166. If the compression ratio in I.C. engine increases, then its thermal efficiency will
  1. Decrease
  2. Increase
  3. remain same

Answer:B

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167. The brake power is the power available
  1. in the engine cylinder
  2. at the crank shaft
  3. at the crank pin
  4. none of these

Answer:B

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168. The volumetric efficiency of a well-designed engine may be
  1. 30 to 40%
  2. 40 to 60%
  3. 60 to 70%
  4. 75 to 90%

Answer:D

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169. A long delay period in compression ignition engines gives a more rapid rise in pressure which causes knocking.
  1. Yes
  2. No

Answer:A

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170. A supercharged engine as compared to an ordinary engine
  1. is lighter
  2. requires smaller foundations
  3. consumes less lubricating oil
  4. all of these

Answer:D

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171. A supercharged engine as compared to an ordinary engine
  1. is lighter
  2. requires smaller foundations
  3. consumes less lubricating oil
  4. all of these

Answer:D

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172. Diesel as compared to petrol is
  1. highly ignitable
  2. more difficult to ignite
  3. less difficult to ignite
  4. none of these

Answer:B

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173. Thermal efficiency of a two stroke cycle engine is __________ a four stroke cycle engine
  1. equal to
  2. less than
  3. greater than

Answer:B

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174. The probability of knocking in diesel engines is increased by
  1. high self-ignition temperature
  2. low volatility
  3. higher viscosity
  4. all of these

Answer:D

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175. The firing order in an I.C. engine depends upon
  1. arrangement of the cylinders
  2. design of crankshaft
  3. number of cylinders
  4. all of these

Answer:D

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176. The pressure at the end of compression, in diesel engines, is approximately
  1. 10 bar
  2. 20 bar
  3. 25 bar
  4. 35 bar

Answer:D

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177. The detonation is also called knocking or pinking
  1. Yes
  2. No

Answer:A

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178. During idling, a petrol engine requires __________ mixture
  1. Lean
  2. Rich
  3. chemically correct

Answer:B

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179. The ignition quality of diesel oil is expressed by
  1. cetane number
  2. octane number
  3. calorific value
  4. none of these

Answer:A

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180. The knocking in spark ignition engines can be reduced by
  1. retarding the spark
  2. increasing the engine speed
  3. both (a) and (b)
  4. none of these

Answer:C

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181. Spark plugs in automobiles generally have a gap between
  1. 0.3 to 0.7 mm
  2. 0.2 to 0.8 mm
  3. 0.4 to 0.9 mm
  4. 0.6 to 1.8 mm

Answer:D

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182. The injection of fuel by external source is not required in case of engines working on Otto cycle.
  1. Yes
  2. No

Answer:A

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183. In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the
  1. beginning of suction stroke
  2. end of suction stroke
  3. beginning of exhaust stroke
  4. end of exhaust stroke

Answer:A

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184. The effective inhibitor of pre-ignition is
  1. Alcohol
  2. Water
  3. Lead
  4. none of these

Answer:B

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185. The air standard efficiency of an I.C. engine depends on
  1. compression ratio
  2. speed of engine
  3. fuel used
  4. none of these

Answer:C

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186. The mean effective pressure of a diesel engine having fixed compression ratio will __________ if cut off ratio decreases.
  1. Increase
  2. Decrease

Answer:B

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187. The fuels in order of decreasing knock tendency for spark ignition engines are
  1. paraffins, aromatics, napthenes
  2. napthenes, paraffins, aromatics
  3. napthenes, aromatics, paraffins
  4. paraffins, napthenes, aromatics

Answer:D

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