IC Engine MCQ Objective Question and Answers Part 2

Internal Combustion Engine ( IC Engine ) Multiple Choice Question and Answers , MCQ Objective Question for Mechanical Engineering

IC Engine MCQ Objective : Part 1 | Part 2 | Part 3

31. Compression loss in I.C engines occurs due to
(a) leaking piston rings
(b) use of thick head gasket
(c) clogged air-inlet slots
(d) increase in clearance volume caused b bearing-bushing wear
(e) all of the above.
Ans: e

32. The specific fuel consumption per BH hour for a petrol engine is approximately
(a) 0.15 kg
(b) 0.2 kg
(c) 0.25 kg
(d) 0.3kg
(e) 0.35 kg.
Ans: c

33. The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is
(a) more
(b) loss
(c) same
(d) may be more or less depending on engine capacity
(e) unpredictable.
Ans: b

34. The inlet value of a four stroke cycle I.C engine remains open for nearly
(a) 180°
(b) 125°
(c) 235°
(d) 200°
(e) 275°.
Ans: c

35. Which of the following is not an interns combustion engine
(a) 2-stroke petrol engine
(b) 4-stroke petrol engine
(c) diesel engine
(d) gas turbine
(e) steam turbine.
Ans: e

36. Pick up the false statement
(a) Thermal efficiency of diesel engine i about 34%
(b) Theoretically correct mixture of air am petrol is approximately 15 : 1
(c) High speed compression engines operate on dual combustion cycle
(d) Diesel engines are compression ignition engines
(e) S.I. engines are quality-governed engines.
Ans: e

37. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the
(a) exhaust will be smoky
(b) piston rings would stick into piston grooves
(c) exhaust temperature will be high
(d) engine starts overheating
(e) scavenging occurs.
Ans: e

38. The output of a diesel engine can be increased without increasing the engine revolution or size in following way
(a) feeding more fuel
(b) increasing flywheel size
(c) heating incoming air
(d) scavenging
(e) supercharging.
Ans: e

39. It the temperature of intake air in IC engines is lowered, then its efficiency will
(a) increase
(b) decrease
(c) remain same
(d) increase upto certain limit and then decrease
(e) decrease upto certain limit and then in-crease.
Ans: a

40. In a typical medium speed 4-stroke cycle diesel engine
(a) compression starts at 35° after bottom dead center and ends at top dead center
(b) compression starts at bottom dead center and ends at top dead center
(c) compression starts at 10° before bottom dead center and, ends just before top dead center
(d) may start and end anywhere
(e) none of the above.
Ans: a

41. For the same compression ratio
(a) Otto cycle is more efficient than the Diesel
(b) Diesel cycle is more efficient’than Otto
(c) both Otto and Diesel cycles are, equally efficient
(d) compression ratio has nothing to do with efficiency
(e) which is more efficient would depend on engine capacity.
Ans: a

42. The process of breaking up or a liquid into fine droplets by spraying is called
(a) vaporization
(b) carburetion
(c) ionisation
(d) injection
(e) atomisation.
Ans: e

43. As a result of detonation in an I.C. engine, following parameter attains very high value
(a) peak pressure
(b) rate of rise of pressure
(c) rate of rise of temperature
(d) peak temperature
(e) rate of rise of horse-power.
Ans: b

44. Which of the following statements is correct?
(a) All the irreversible engines have same efficiency
(b) All the reversible engines have same efficiency
(c) Both Rankine and Caront cycles have same efficiency between same temperature limits
(d) All reversible engines working between same temperature limits have same-efficiency
(e) Between same temperature limits, both petrol and diesel engines have same efficiency.
Ans: d

45. Most high speed compression engines operate on
(a) Diesel cycle
(b) Otto cycle
(c) Dual combustion cycle
(d) Special type of air cycle
(e) Carnot cycle.
Ans: c

48. The accumulation of carbon in a cylinder results in increase of
(a) clearance volume
(b) volumetric efficiency
(c) ignition time
(d) effective compression ratio
(e) valve travel time.
Ans: d

49. Which of the following medium is compressed in a Diesel engine cylinder
(a) air aione
(b) air and fuel
(c) air and lub oil
(d) fuel alone
(e) air, fuel and lub oil.
Ans: a

54. The air-fuel ratio of the petrol engine is controlled by
(a) fuel pump
(b) governor
(c) injector
(d) carburettor
(e) scavenging.
Ans: d

55. In a typical medium speed, 4-stroke cycle diesel engine
(a) fuel injection starts at 10° before to dead center and ends at 20° after tor dead center
(b) fuel injection starts at top dead center and ends at 20° after top dead center
(c) fuel injection starts at just before top dead center and ends just after top deac center
(d) may start and end anywhere
(e) none of the above.
Ans: a

56. Diesel fuel, compared to petrol is
(a) less difficult to ignite
(b) just about the same difficult to ignite
(c) more difficult to ignite
(d) highly ignitable
(e) none of the above.
Ans: c

57. In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of
(a) 250°C
(b) 500°C
(c) 1000°C
(d) 150CPC
(e) 2000°C.
Ans: c

58. When crude oil is heated, then which of the following hydrocarbon is given off first.
(a) kerosene
(b) gasoline
(c) paraffin
(d) diesel
(e) natural gas.
Ans: e

59. The rating of a diesel engine, with increase in air inlet temperature, will
(a) increase linearly
(b) decrease linearly
(c) increase parabolically
(d) decrease parabolically
(e) first decrease linearly and then increase parabolically.
Ans: b

60. A 75 cc engine has following parameter as 75 cc
(a) fuel tank capacity
(b) lub oil capacity
(c) swept volume
(d) cylinder volume
(e) clearance volume.
Ans: c

61. A heat engine utilities the
(a) calorific value of oil
(b) low heat value of
(c) high heat value of oil
(d) mean heat value of oil
(e) all of the above.
Ans: c

62. Gaseous-fuel guarantees are based on
(a) calorific value of oil
(b) low heat value of oil
(c) high heat value of oil
(d) mean heat value of oil
(e) all of the above.
Ans: b

63. Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads
(a) the friction is high
(b) the friction is unpredictable
(c) the small difference in cooling water temperature or in internal friction has a disproportionate effect
(d) the engine is rarely operated
(e) none of the above.
Ans: c

64. Polymerisation is a chemical process in which molecules of a compound become
(a) larger
(b) slowed down
(c) smaller
(d) liquid
(e) gaseous.
Ans: a

65. The term scavenging is generally associated with
(a) 2-stroke cycle engines
(b) 4-stroke cycle engines
(c) aeroplane engines
(d) diesel engines
(e) high efficiency engines.
Ans: e

66. In diesel engine, the compression ratio in comparison to expansion ratio is
(a) same
(b) less
(G) more
(d) variable
(e) more/less depending on engine capacity.
Ans: c

67. The cam shaft of a four stroke I.C. engine running at 1500 rmp will run at
(a) 1500 rpm
(b) 750 rpm
(c) 3000 rpm
(d) any value independent of engine speed
(e) none of the above.
Ans: b