i c engines MCQs – Page 2

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

i c engines Mcqs
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