RBI Grade B officer - Internal Combustion 1000+ MCQ [Solved] PDF Download

1. 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

2. The delay period in compression ignition engines depends upon
A. Temperature and pressure in the cylinder at the time of injection
B. Nature of the fuel mixture strength
C. Relative velocity between the fuel injection and air turbulence pressure of residual gases
D. All of the above
Answer : D

3. 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

4. The air-fuel ratio of the petrol engine is controlled by
A. Carburettor
B. Injector
C. Governor
D. None of these
Answer : A

5. The exhaust valve in a four stroke cycle petrol engine
A. Opens at 50° before bottom dead centre and closes at 15° after top dead centre
B. Opens at bottom dead centre and closes at top dead centre
C. Opens at 50° after bottom dead centre and closes at 15° before top dead centre
D. May open and close anywhere
Answer : A

6. The maximum temperature in the I.C. engine cylinder is of the order of
A. 500-1000°C
B. 1000-1500°C
C. 1500-2000°C
D. 2000-2500°C
Answer : D

7. The voltage required to produce a spark across the gap, between the sparking points is
A. 2000 to 4000 volts
B. 4000 to 6000 volts
C. 6000 to 10,000 volts
D. 10,000 to 12,000 volts
Answer : C

8. Antiknock for compression ignition engines is
A. Napthene
B. Tetra ethyl lead
C. Amyl nitrate
D. Hexadecane
Answer : C

9. Polymerisation is a chemical process in which molecules of a compound become
A. Larger
B. Slowed down
C. Smaller
D. Liquid
Answer : A

10. 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

11. In a four stroke cycle diesel engine, the exhaust valve
A. Opens at 30° before bottom dead centre and closes at 10° after top dead centre
B. Opens at 30° after bottom dead centre and closes at 10° before top dead centre
C. Opens at bottom dead centre and closes at top dead centre
D. May open and close anywhere
Answer : A

12. 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

13. Most high speed compression engines operate on
A. Otto cycle
B. Diesel cycle
C. Dual cycle
D. Carnot cycle
Answer : C

14. The reason for supercharging in any engine is to
A. Increase efficiency
B. Increase power
C. Reduce weight and bulk for a given output
D. Effect fuel economy
Answer : C

15. The size of inlet valve of an engine in comparison to exhaust valve is
A. More
B. Less
C. Same
D. More/less depending on capacity of engine
Answer : B

16. A diesel engine has
A. 1 valve
B. 2 valves
C. 3 valves
D. 4 valves
Answer : C

17. In a four stroke cycle diesel engine, the compression
A. Starts at 40° after bottom dead centre and ends at 10° before top dead centre
B. Starts at 40° before top dead centre and ends at 40° after top dead centre
C. Starts at top dead centre and ends at 40° before bottom dead centre
D. May start and end anywhere
Answer : A

18. When crude oil is heated, then which of the following hydrocarbon is given off first?
A. Kerosene
B. Gasoline
C. Paraffin
D. Natural gas
Answer : D

19. The calorific value of gaseous fuels is expressed in terms of
A. kcal
B. kcal/kg
C. kcal/m²
D. kcal/m³
Answer : D

20. The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will
A. Increase
B. Decrease
C. Be independent
D. May increase or decrease depending on other factors
Answer : B

21. The thermal efficiency of diesel engines is about
A. 15 %
B. 30 %
C. 50 %
D. 70 %
Answer : D

22. 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

23. 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

24. The pressure and temperature at the end of compression stroke in a petrol engine are of the order of
A. 4-6 kg/cm² and 200-250°C
B. 6-12 kg/cm² and 250-350°C
C. 12-20 kg/cm² and 350-450°C
D. 20-30 kg/cm² and 450-500°C
Answer : B

25. A mixture containing 65% of iso-octane and 35% of normal heptane will have
A. Cetane number 65
B. Octane number 65
C. Cetane number 35
D. Octane number 35
Answer : B

26. Pick up the wrong statement about supercharging
A. Supercharging reduces knocking in diesel engines
B. There can be limited supercharging in petrol engines because of detonation
C. Supercharging at high altitudes is essential
D. Supercharging results in fuel economy
Answer : D

27. 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
Answer : A

28. Thermal efficiency of a two stroke cycle engine is ________ a four stroke cycle engine.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : B

29. 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

30. Diesel engine can work on very lean air fuel ratio of the order of 30: 1. A petrol engine can also work on such a lean ratio provided
A. It is properly designed
B. Best quality fuel is used
C. Cannot work as it is impossible
D. Flywheel size is proper
Answer : C

31. Iso-octane (C₈H₁₈) has octane number of
A. 0
B. 50
C. 100
D. 120
Answer : C

32. 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

33. The increase of efficiency of a compression ignition engine, as the load decreases, is due to
A. Higher maximum temperature
B. Qualitative governing
C. Quantitative governing
D. Hit and miss governing
Answer : B

34. The magneto in an automobile is basically
A. Transformer
B. D.C. generator
C. Capacitor
D. Magnetic circuit
Answer : B

35. The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be
A. Higher
B. Lower
C. Remain unaffected
D. None of the above
Answer : A

36. In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have
A. Low density
B. Low temperature
C. Long ignition delay
D. All of these
Answer : D

37. It the temperature of intake air in IC engines is lowered, then its efficiency will
A. Increase
B. Decrease
C. Remain same
D. Increase up to certain limit and then decrease
Answer : A

38. 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

39. The power actually developed by the engine cylinder of an I.C. engine is known as
A. Theoretical power
B. Actual power
C. Indicated power
D. None of these
Answer : C

40. 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

41. 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

42. A diesel engine has
A. One valve
B. Two valves
C. Three valves
D. Four valves
Answer : C

43. 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

44. The reflectivity depends upon
A. Geometry of the reflector
B. Energy of neutrons
C. Properties of the reflector
D. All of these
Answer : D

45. The turbine of the turboprop engine is __________ that of the turbojet engine.
A. Same as
B. Smaller than
C. Bigger than
D. None of these
Answer : C

46. 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

47. By higher octane number of spark ignition fuel, it is meant that the fuel has
A. Higher heating value
B. Higher flash point
C. Lower volatility
D. Longer ignition delay
Answer : D

48. The injection pressure in a diesel engine is about
A. 10 bar
B. 100 bar
C. 150 bar
D. 500 bar
Answer : B

49. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is
A. Same
B. Less
C. More
D. More or less depending on power rating
Answer : C

50. The thermodynamic cycle on which the petrol engine works, is
A. Otto cycle
B. Joule cycle
C. Rankine cycle
D. Stirling cycle
Answer : A