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

1. 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

2. A higher compression ratio causes
A. Pre-ignition
B. Increase in detonation
C. Acceleration in the rate of combustion
D. Any one of these
Answer : D

3. The air standard efficiency of an I.C. engine is given by (where r = Compression ratio, and ? = Ratio of specific heats)
A. 1 - r^{? - 1}
B. 1 + r^{? - 1}
C. 1 - (1/r^{? - 1})
D. None of these
Answer : C

4. Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine.
A. Half
B. Same
C. Double
D. Four times
Answer : A

5. The volumetric efficiency of a well designed engine may be
A. 30 to 40 %
B. 40 to 60 %
C. 60 to 70 %
D. 75 to 90 %
Answer : D

6. The probability of knocking in diesel engines is increased by
A. High self ignition temperature
B. Low volatility
C. Higher viscosity
D. All of these
Answer : D

7. The self ignition temperature of petrol is ________ as compared to diesel oil.
A. Same
B. Lower
C. Higher
D. None of these
Answer : C

8. Pick up the false statement
A. Thermal efficiency of diesel engine is about 34%
B. Theoretically correct mixture of air and petrol is approximately 15:1
C. High speed compression engines operate on dual combustion cycle
D. S.I. engines are quality governed engines
Answer : D

9. The theoretically correct mixture of air and petrol is
A. 10 : 1
B. 15 : 1
C. 20 : 1
D. 25 : 1
Answer : B

10. 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

11. A spark plug gap is kept from
A. 0.3 to 0.7 mm
B. 0.2 to 0.8 mm
C. 0.4 to 0.9 mm
D. 0.6 to 1.0 mm
Answer : A

12. 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

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

14. Diesel as compared to petrol is
A. Highly ignitable
B. More difficult to ignite
C. Less difficult to ignite
D. None of these
Answer : B

15. Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of
A. Plates
B. Pallets
C. Pins
D. All of these
Answer : D

16. The maximum propulsive efficiency of a turbojet engine is at a speed of
A. 1000 km/h
B. 2000 km/h
C. 2400 km/h
D. 3000 km/h
Answer : C

17. As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
A. Increase maximum pressure and maximum temperature
B. Reduce maximum pressure and maximum temperature
C. Increase maximum pressure and decrease maximum temperature
D. Decrease maximum pressure and increase maximum temperature
Answer : B

18. 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

19. The brake power of a diesel engine, keeping other parameters constant, can be increased by
A. Decreasing the density of intake air
B. Increasing the temperature of intake air
C. Increasing the pressure of intake air
D. Decreasing the pressure of intake air
Answer : C

20. The accumulation of carbon in a cylinder results in increase of
A. Clearance volume
B. Volumetric efficiency
C. Ignition time
D. Effective compression ratio
Answer : D

21. 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

22. Scavenging air in diesel engine means
A. Air used for combustion sent under pressure
B. Forced air for cooling cylinder
C. Burnt air containing products of combustion
D. Air used for forcing burnt gases out of engine's cylinder during the exhaust period
Answer : D

23. In a diesel engine, the fuel is ignited by
A. Spark
B. Injected fuel
C. Heat resulting from compressing air that is supplied for combustion
D. Ignition
Answer : C

24. The actual volume of fresh charge admitted in 4-stroke petrol engine is
A. Equal to stroke volume
B. Equal to stroke volume and clearance volume
C. Less than stroke volume
D. More than stroke volume
Answer : C

25. 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

26. The basic requirement of a good combustion chamber is
A. Minimum turbulence
B. Low compression ratio
C. High thermal efficiency and power output
D. Low volumetric efficiency
Answer : C

27. If the temperature of intake air in internal combustion engine increases, then its efficiency will
A. Remain same
B. Decrease
C. Increase
D. None of these
Answer : B

28. A supercharged engine as compared to an ordinary engine
A. Requires smaller foundation
B. Is lighter
C. Consumes less lubricating oil
D. All of these
Answer : D

29. Which of the following statement is wrong?
A. A four stroke cycle engine develops twice the power as that of a two stroke cycle engine
B. For the same power developed, a four stroke cycle engine is lighter, less bulky and occupies less floor area
C. The petrol engines are costly than diesel engines
D. All of the above
Answer : D

30. The air-fuel ratio in petrol engines is controlled by
A. Controlling valve opening/closing
B. Governing
C. Injection
D. Carburetion
Answer : D

31. An engine indicator is used to determine the following
A. Speed
B. Temperature
C. Volume of cylinder
D. m.e.p. and I.H.P.
Answer : D

32. The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is
A. More
B. Less
C. Same
D. May be more or less depending on engine capacity
Answer : B

33. 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

34. The process of breaking up or a liquid into fine droplets by spraying is called
A. Vaporisation
B. Carburetion
C. Ionisation
D. Atomisation
Answer : D

35. 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

36. The fuel in diesel engine is normally injected at pressure of
A. 5-10 kg/cm²
B. 20-25 kg/cm²
C. 60-80 kg/cm²
D. 90-130 kg/cm²
Answer : D

37. The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is
A. Same
B. More
C. Less
D. Less or more depending on operating conditions
Answer : B

38. 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 dead center
D. May start and end anywhere
Answer : A

39. A 75 cc engine has following parameter as 75 cc
A. Fuel tank capacity
B. Lube oil capacity
C. Swept volume
D. Cylinder volume
Answer : C

40. Which of the following medium is compressed in a Diesel engine cylinder?
A. Air alone
B. Air and fuel
C. Air and lub oil
D. Fuel alone
Answer : A

41. 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

42. The operation of forcing additional air under pressure into the engine cylinder is known as
A. Supercharging
B. Carburetion
C. Turbulence
D. Delay period
Answer : A

43. 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

44. 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

45. The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at
A. 1500 rpm
B. 750 rpm
C. 3000 rpm
D. Any value independent of engine speed
Answer : B

46. 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

47. 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

48. Crankcase explosion in I.C. engines usually occurs as
A. First a mild explosion followed by a bi explosion
B. First a big explosion followed by a mil explosion
C. Both mild and big explosions occurs simultaneously
D. Never occurs
Answer : A

49. Morse test can be conducted for
A. Petrol engines
B. Diesel engines
C. Multi cylinder engines
D. All of these
Answer : C

50. Which of the following does not relate to a compression ignition engine?
A. Fuel pump
B. Fuel injector
C. Governor
D. Carburettor
Answer : D