RRB JE - Internal Combustion 1000+ MCQ [Solved] PDF Download

1. In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the
A. Beginning of suction stroke
B. End of suction stroke
C. Beginning of exhaust stroke
D. End of exhaust stroke
Answer : A

2. If the speed of the engine is increased, the indicated power will
A. Increase
B. Decrease
C. Remain same
D. None of these
Answer : A

3. Pour point of fuel oil is the
A. 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
B. Temperature at which it solidifies or congeals
C. It catches fire without external aid
D. Indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off
Answer : B

4. Air fuel ratio for idling speed of a petrol engine is approximately
A. 1 : 1
B. 5 : 1
C. 10 : 1
D. 15 : 1
Answer : C

5. The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called
A. Mechanical efficiency
B. Overall efficiency
C. Volumetric efficiency
D. Relative efficiency
Answer : C

6. An hmh flame speed is obtained in diesel engine when air fuel ratio is
A. Uniform throughout the mixture
B. Chemically correct mixture
C. About 35% of rich mixture
D. About 10% of rich mixture
Answer : D

7. Which of the following statement is wrong?
A. In compression ignition engines, detonation occurs near the beginning of combustion.
B. Since the fuel, in compression ignition engines, is injected at the end of compression stroke, therefore, there will be no pre-ignition.
C. To eliminate knock in compression ignition engines, we want to achieve auto-ignition not early and desire a long delay period.
D. In compression ignition engines, because of heterogeneous mixture, the rate of pressure rise is comparatively lower.
Answer : C

8. In a naturally aspirated diesel engine, the air is supplied by
A. A supercharger
B. A centrifugal blower
C. A vacuum chamber
D. An injection tube
Answer : C

9. A fuel of cetane number 40 has the same ignition quality as a mixture of
A. 40% cetane and 60% alpha methyl naphthalene
B. 40% alpha methyl naphthalene and 60% cetane
C. 40% petrol and 60% diesel
D. 40% diesel and 60% petrol
Answer : A

10. Compression ratio of I.C. Engines is
A. The ratio of volumes of air in cylinder before compression stroke and after compression stroke
B. Volume displaced by piston per stroke and clearance volume in cylinder
C. Ratio of pressure after compression and before compression
D. Swept volume/cylinder volume
Answer : A

11. Engine pistons are usually made of aluminium alloy because it
A. Is lighter
B. Wear is less
C. Absorbs shocks
D. Is stronger
Answer : A

12. The frictional power (F.P.) is given by
A. F.P. = B.P. - I.P.
B. F.P. = I.P. - B.P.
C. F.P. = B.P./I.P.
D. F.P. = I.P./B.P.
Answer : B

13. A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of
A. 75% iso-octane and 25% normal heptane
B. 75% normal heptane and 25% iso-octane
C. 75% petrol and 25% diesel
D. 75% diesel and 25% petrol
Answer : A

14. The expansion of fuel in a four stroke cycle diesel engine
A. Starts at 15° before top dead centre and ends at 30° after top dead centre
B. Starts at top dead centre and ends at 30° after top dead centre
C. Starts at 15° after top dead centre and ends at 30° before bottom dead centre
D. May start and end anywhere
Answer : C

15. The ratio of the brake power to the indicated power is called
A. Mechanical efficiency
B. Overall efficiency
C. Indicated thermal efficiency
D. Volumetric efficiency
Answer : A

16. The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
A. Morse test
B. Prony brake test
C. Motoring test
D. Heat balance test
Answer : A

17. A 5 BHP engine running at full load would consume diesel of the order of
A. 0.3 kg/hr
B. 1 kg/hr
C. 3 kg/hr
D. 5 kg/hr
Answer : B

18. The object of providing masked inlet valve in the air passage of compression ignition engines is to
A. Enhance flow rate
B. Control air flow
C. Induce primary swirl
D. Induce secondary turbulence
Answer : C

19. The loud pulsating noise heard within the cylinder of an internal combustion engine is known as
A. Detonation
B. Turbulence
C. Pre-ignition
D. Supercharging
Answer : A

20. In an internal combustion engine, the process of removing the burnt gases from the combustion chamber of the engine cylinder is known as
A. Scavenging
B. Detonation
C. Supercharging
D. Polymerisation
Answer : A

21. The mechanical efficiency (?m) of the engine is given by
A. ?_m = B.P/I.P
B. ?_m = I.P/B.P
C. ?_m = (B.P × I.P)/100
D. None of these
Answer : A

22. The specific fuel consumption per BHP hour for diesel engine is approximately
A. 0.15 kg
B. 0.2 kg
C. 0.25 kg
D. 0.3 kg
Answer : B

23. The air standard efficiency of an I.C. engine depends on
A. Fuel used
B. Speed of engine
C. Compression ratio
D. None of these
Answer : C

24. In the crankcase method of scavenging, the air pressure is produced by
A. Supercharger
B. Centrifugal pump
C. Natural aspirator
D. Movement of engine piston
Answer : D

25. The colour of exhaust from diesel engine is generally
A. White
B. Bluish
C. Black
D. Violet
Answer : C

26. 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
Answer : C

27. In a diesel engine, the duration between the time of injection and ignition, is known as
A. Pre-ignition period
B. Delay period
C. Period of ignition
D. Burning period
Answer : B

28. Combustion in compression ignition engines is
A. Homogeneous
B. Heterogeneous
C. Both (A) and (B)
D. Laminar
Answer : B

29. The pressure at the end of compression, in diesel engines, is approximately
A. 10 bar
B. 20 bar
C. 25 bar
D. 35 bar
Answer : D

30. Which of the following statement is correct?
A. Compression ratio for petrol engines varies from 6 to 10
B. Higher compression ratio in diesel engines results in higher pressures
C. Petrol engines work on Otto cycle
D. All of the above
Answer : D

31. The correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines is
A. Four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine
B. Four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine
C. Four stroke C.I. engine, two stroke S.I. engine, four stroke S.I. engine
D. Two stroke S.I. engine, four stroke S.I. engine, four stroke C.I. engine
Answer : A

32. 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. 2000°C
Answer : C

33. The minimum cranking speed in case of petrol engine is about
A. Half the operating speed
B. One fourth of operating speed
C. 250 - 300 rpm
D. 60 - 80 rpm
Answer : D

34. If V? is the jet velocity and V? is the vehicle velocity, then the propulsive efficiency of a rocket is given by
A. [2(V?/V?)]/ [1 + (V?/V?)²]
B. (V?/V?)/ [1 + (V?/V?)²]
C. V?/(V? + V?)
D. V?/(V? + V?)
Answer : A

35. 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. All of the above
Answer : D

36. The cetane (C₁₆H₃₄) which is a straight chain paraffin, is assigned a cetane number of
A. 0
B. 50
C. 100
D. 120
Answer : C

37. The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the
A. Jet area is automatically varied depending on the suction
B. The flow from the main jet is diverted to the compensating jet with increase in speed
C. The diameter of the jet is constant and the discharge coefficient is invariant
D. Flow is produced due to the static head in the float chamber
Answer : D

38. The purpose of testing an internal combustion engine is
A. To determine the information, which cannot be obtained by calculations
B. To conform the data used in design, the validity of which may be doubtful
C. To satisfy the customer regarding the performance of the engine
D. All of the above
Answer : D

39. Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged?
A. Yes
B. No
C. To some extent
D. Unpredictable
Answer : B

40. If the intake air temperature of I.C. engine increases, its efficiency will
A. Increase
B. Decrease
C. Remain same
D. None of these
Answer : B

41. The compression ignition engines are governed by
A. Hit and miss governing
B. Qualitative governing
C. Quantitative governing
D. Combination of (B) and (C)
Answer : B

42. The fuel valve in a four stroke cycle diesel engine
A. Opens at 15° after top dead centre and closes at 20° before bottom dead centre
B. Opens at 15° before top dead centre and closes at 20° after top dead centre
C. Opens at top dead centre and closes at bottom dead centre
D. May open and close anywhere
Answer : B

43. A diesel engine as compared to petrol engine (both running and rated load) is
A. More efficient
B. Less efficient
C. Equally efficient
D. Other factors will decide it
Answer : A

44. The ratio of the indicated thermal efficiency to the air standard efficiency is known as
A. Mechanical efficiency
B. Overall efficiency
C. Volumetric efficiency
D. Relative efficiency
Answer : D

45. In case of gas turbines, the gaseous fuel consumption guarantees are based on
A. High heat value
B. Low heat value
C. Net calorific value
D. Calorific value
Answer : B

46. The specific fuel consumption per B.P. hour for a diesel engine is about
A. 0.2 kg
B. 0.25 kg
C. 0.3 kg
D. 0.35 kg
Answer : A

47. A diesel engine is _________ as compared to petrol engine, both running at rated load.
A. Equally efficient
B. Less efficient
C. More efficient
D. None of these
Answer : C

48. Number of working strokes per min. for a two stroke cycle engine is _________ the speed of the engine in r.p.m.
A. Equal to
B. One-half
C. Twice
D. Four-times
Answer : A

49. All heat engines utilize
A. Low heat value of oil
B. High heat value of oil
C. Net calorific value of oil
D. Calorific value of fuel
Answer : A

50. Which of the following statement is correct regarding petrol engines?
A. A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure
B. The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug
C. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition
D. All of the above
Answer : B