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i c engines MCQs

Practise focused i c engines questions with marked answers for exam preparation and subject revision.

i c engines Mcqs
1. The ignition coil in diesel engines produces voltage of the order of________________?
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A. 20,000 volts

B. 6 to 12 volts

C. 80,000 volts

D. 240 volts

E. 1000 volts

2. Method of governing used in petrol engine is________________?
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A. combined governing

B. hit and miss governing

C. partial governing

D. quantity governing

E. quality governing

3. Which is false statement about advantages of V-type engine_________________?
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A. improved distribution of air to cylinder

B. compact design requiring lesser space

C. reduced torsional vibration because of shorter crankshaft

D. less overhead clearance

E. casting less liable to distortion

4. Diesel engines as compared to petrol engines require ______________________?
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A. no flywheel

B. bigger flywheel

C. flywheel whose size may be less or more depending on several other fac-tors

D. smaller flywheel

E. same size flywheel

5. The thermal efficiency of a two cycle engine as compared to four cycle engine is_________________?
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A. it may be less or more depending on several other factors

B. same

C. less

D. more

E. more upto some load and then less

6. Normal heptane_______________?
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A. helps to resist auto-ignition

B. accelerates auto-ignition

C. retards auto-ignition

D. has no relation with auto-ighition

E. does not affect auto-ignition

7. Carbon residue in diesel oil should not be more than___________________?
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A. 0.50%

B. 1%

C. 0.10%

D. 0.001%

E. 0.01%

8. In case of gas turbines, the gaseous fuel consumption guarantees are based on________________?
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A. net calorific value

B. middle heat value

C. high heat value

D. calorific value

E. low heat value
9. Iso-oct ,ne________________?
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A. is an index of detonation quality

B. has octane number of 100

C. has octane number of 50

D. is an index of knocking quality

E. has octane number of 0

10. In petrol engine using a fixed octane rating fuel and fixed compression ratio, super charging will_________________?
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A. increase or decrease knocking tendency depending on strength and time of spark

B. not affect the knocking tendency

C. unpredictable

D. decrease the knocking tendency

E. increase the knocking tendency
11. Pick up the wrong statement?
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A. thermal efficiency of 4-stroke engine is more due to positive scavenging

B. 2-stroke engine can run in any direction

C. petrol engines work on otto cycle

D. In 4-stroke engine, a power stroke is obtained in 4-strokes

E. petrol engines occupy more space than diesel engines for same power output
12. The firing order in a six stroke I.C. engine is_________________?
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A. 1-5-2-6-3-4

B. 1-6-2-5-4-3

C. 1-4-2-5-6-3

D. 1-3-6-5-2-4

E. 1-5-3-4-2-6
13. Auto-ignition reaction time for petrol engine first decreases with increase in fuel air ratio, reaches a minimum value and then increases with subsequent increase in fuel air ratio. The minimum value occurs in the region of________________?
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A. Rich mixture

B. Chemically correct fuel air ratio

C. Lean mixture

D. Unpredictable

14. For the same compression ratio_____________________?
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A. Otto cycle is more efficient than the Diesel

B. Diesel cycle is more efficientthan 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

15. In a typical medium speed 4-stroke cycle diesel engine________________?
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A. none of the above

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. compression starts at 35 after bottom dead center and ends at top dead center
16. All heat engines utilize_____________________?
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A. all of the above

B. net claorific value of oil

C. high heat value of oil

D. low heat value of oil

E. calorific value of fuel

17. Detonation is caused by the following unstable compounds______________________?
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A. ketones and sulphur compounds

B. peroxides, aldehydes, oxides and sul-phides

C. aldehydes, oxides and ketones

D. peroxides, aldehydes and ketones

E. none of the above

18. The ignition of charge by some hot surface in the engine cylinder before operation of spark plug is known as________________?
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A. retarded ignition

B. auto ignition

C. preignition

D. detonation

E. accelerated ignition

19. The mean effective pressure obtained from engine indicator indicates the________________?
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A. instantaneous pressure at any instant

B. exhaust pressure

C. average pressure

D. maximum pressure developed

E. minimum pressure

20. Supercharging is the process of_____________________?
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A. supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere

B. injecting excess fuel for raising more load

C. providing forced cooling air

D. raising exhaust pressure

E. supplying compressed air to remove combustion products fully

21. Supercharging is essential in_____________?
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A. marine engines

B. diesel engines

C. gas turbines

D. aircraft engines

E. petrol engines

22. A 4-stroke diesel engine needs about following amount of air_________________?
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A. 75000 cc per min. per h.p.

B. 75 cc per min. per h.p.

C. 750 cc per min. per h.p.

D. 750000 cc per min. per h.p

E. 7500 cc per min. per h.p.

23. The specific fuel consumption for a petrol engine first decreases with increase in fuel air ratio and then increases with further increase in fuel air ratio. The minimum value occurs in the range of__________________?
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A. none of the above

B. lean mixture

C. chemically correct mixture

D. rich mixture

E. unpredictable

24. In a typical medium speed, 4-stroke cycle diesel engine ___________________?
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A. fuel injection starts at top dead center and ends at 20 after top dead center

B. none of the above

C. fuel injection starts at just before top dead center and ends just after top deac center

D. fuelinjection starts at 10 before to dead center and ends at 20 after tor dead center

E. may start and end anywhere

25. Pour point of fuel oil is the_________________?
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A. temperature at which it solidifies or congeals

B. 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

C. temperature at which it flows easily

D. it catches fire without external aid

E. indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off

26. Engine pistons are usually made of aluminium alloy because it_________________?
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A. is lighter

B. wears less

C. is stronger

D. absorbs shocks

E. does not react with fuel and lub oil

27. Ignition quailty of petrol is expressed by___________________?
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A. distillation temperature

B. octane number

C. calorific value

D. cetane number

E. self ignition temperature

28. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft___________________?
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A. 4

B. 8

C. 2-Jan

D. 2

E. 1

29. The following volume of air is required for consuming 1 liter of fuel by a four stroke engine_______________?
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A. 15-18 m3

B. 5 m3

C. 1 m3

D. 9-10 m3

E. 5-6 m3

30. Violent sound pulsations within the cylinder of an I.C. engine are caused due to_________________?
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A. heavy turbulence

B. improved scavenging

C. preignition

D. detonation

E. heavy supercharging

31. The m.e.p. of a diesel cycle having fixed compression ratio with increase in cut-off will_________________?
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A. increase

B. decreae

C. unpredictable

D. depend on other factors

E. be unaffected

32. The inlet value of a four stroke cycle I.C engine remains open for nearly___________________?
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A. 200

B. 125

C. 235

D. 275

E. 180

33. Hot air standard diesel cycle efficiency with increase in value of C_______________?
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A. unpredictable

B. increases

C. decreases

D. remains unaffected

E. depends on other factors

34. Detonation can be controlled by_____________________?
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A. varying compression ratio

B. using lian mixture

C. retarding the spark timing

D. reducing the r.p.m.

E. increasing inlet pressure

35. In petrol engines, advancing the spark timing will_______________?
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A. increase the knocking tendency

B. decrease the knocking tendency

C. increase or decrease knocking tendency depending on strenght and time of spark

D. not affect the knocking tendncy

E. unpredictable

36. Which of the following engines can work on very lean mixture__________________?
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A. C.I. engine

B. S.I. engine

C. two stroke engine

D. four stroke engine

E. all of the above

37. In carburettors, the top of the fuel jet with reference to the level in the float chamber is kept at_________________?
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A. may be anywhere

B. varies from situation to situation

C. slightly higher level

D. same level

E. slightly lower level

38. The theoretically correct air fuel ratio for petrol engine is of the order of___________________?
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A. 20:01

B. 9:01

C. 6:01

D. 12:01

E. 15 : 1
39. In petrol engines, the maximum power is developed corresponding to relative fuel air ratio of________________?
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A. 0.85

B. 1

C. 1.1 to 1.3

D. 1.2 to 1.5

40. The actual volume of fresh charge admitted in 4-stroke petrol engine is_________________?
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A. equal to stroke volume

B. less than stroke volume

C. equal to stroke volume and clearance volume

D. more than stroke volume

E. more than cylinder volume

41. Which is correct statement about reaction time for autoignition of fuel and the fuel air ratio__________________?
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A. non of the above

B. chemically correct mixture has mini-mum reaction time

C. rich mixture has high reaction time

D. all of the above

E. lean mixture has high reaction time

42. The system of lubrication used for motor cycles and scooters is by________________?
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A. forced lubrication system

B. mixing about 5% lub oil with petrol

C. applying grease under pressure

D. wet sump method

E. splash lubrication

43. The thermal efficiency of a petrol engine of two stroke with crank case scavenging as compared to four stroke petrol engine with same comperssion ratio will be_____________________?
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A. depends on size of engine

B. same

C. higher

D. unpredictable.

E. lower
44. The air-fuel ratio in petrol engines-is controlled by__________________?
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A. carburettion

B. controlling valve opening/closing

C. scavenging and supercharging

D. injection

E. governing

45. In the crankcase method of scavenging, the air pressure is produced by_________________?
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A. movement of engine piston

B. reciprocating pump

C. centrifugal pump

D. natural aspirator

E. supercharger

46. In a diesel engine, the fuel is ignited by___________________?
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A. ignition

B. injected fuel

C. spark

D. heat resulting from compressing air that is supplied for combustion

E. combustion chamber

47. The self-ignition temperature of diesel oil compared to petrol is_________________?
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A. depends on quality of fuel

B. lower

C. higher

D. same

E. unpredictable

48. Cetane___________________?
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A. has 100 cetane number

B. has zero cetane number

C. is a straight chain paraffin

D. determines the efficiency of an I.C. engine

E. helps detonation

49. Solid injection in I.C. engines refers to injection of________________?
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A. liquid fuel only

B. solid fuel

C. does not exist

D. liquid fuel and air

E. solid fuel and air

50. The termal efficiency of a petrol engine at design load is around_________________?
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A. 40%

B. 15%.

C. 50%

D. 30%

E. 90%