Internal Combustion 1000+ MCQ with answer for SSC CGL

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

2. 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

3. 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

4. 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

5. The rating of a diesel engine, with increase in air inlet temperature, will
A. Increase linearly
B. Decrease linearly
C. Increase parabolically
D. Decrease parabolically
Answer : B

6. 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

7. Which of the following is the lightest and most volatile liquid fuel?
A. Diesel
B. Kerosene
C. Fuel oil
D. Gasoline
Answer : D

8. A two stroke cycle engine gives ________ the number of power strokes as compared to the four stroke cycle engine, at the same engine speed.
A. Half
B. Same
C. Double
D. Four times
Answer : C

9. 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

10. 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

11. 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

12. The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres)
A. B.P = (Wl × 2?N)/60 watts
B. B.P = [(W - S) ?DN]/60 watts
C. B.P = [(W - S) ? (D + d) N]/60 watts
D. All of these
Answer : D

13. 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

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

15. 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

16. The firing order in an I.C. engine depends upon
A. Arrangement of the cylinders
B. Design of crankshaft
C. Number of cylinders
D. All of these
Answer : D

17. 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

18. In diesel engine, the compression ratio in comparison to expansion ratio is
A. Same
B. Less
C. More
D. Variable
Answer : C

19. In petrol engines, the delay period is of the order of
A. 0.001 second
B. 0.002 second
C. 0.003 second
D. 0.004 second
Answer : B

20. 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

21. The brake power is the power available
A. In the engine cylinder
B. At the crank shaft
C. At the crank pin
D. None of these
Answer : B

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

23. Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads
A. The friction is high
B. The friction is unpredictable
C. The small difference in cooling water temperature or in internal friction has a disproportionate effect
D. The engine is rarely operated
Answer : C

24. The air-fuel ratio of the petrol engine is controlled by
A. Fuel pump
B. Governor
C. Injector
D. Carburettor
Answer : D

25. The following volume of air is required for consuming 1 litre of fuel by a four stroke engine
A. 1 m3
B. 5 m3
C. 56 m3
D. 910 m3
Answer : D

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

27. 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

28. 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

29. In loop scavenging, the top of the piston is
A. Flat
B. Contoured
C. Slanted
D. Depressed
Answer : B

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

31. The pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.
A. Equal to
B. Below
C. Above
D. None of these
Answer : C

32. 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

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

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

35. In a four stroke cycle diesel engine, the inlet valve
A. Opens at 20° before top dead centre and closes at 40° after bottom dead centre
B. Opens at 20° after top dead centre and closes at 20° before bottom dead centre
C. Opens at top dead centre and closes at bottom dead centre
D. May open and close anywhere
Answer : A

36. Most high speed compression engines operate on
A. Diesel cycle
B. Otto cycle
C. Dual combustion cycle
D. Special type of air cycle
Answer : C

37. The knocking in diesel engines may be prevented by
A. Reducing the delay period
B. Raising the compression ratio
C. Increasing the inlet pressure of air
D. All of these
Answer : D

38. 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

39. The theoretically correct air fuel ratio for petrol engine is of the order of
A. 6 : 1
B. 9 : 1
C. 12 : 1
D. 15 : 1
Answer : D

40. 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

41. 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

42. If V? is the jet velocity and V? is the vehicle velocity, then propulsive efficiency of a turbojet engine is
A. V?/(V? + V?)
B. V?/(V? + V?)
C. 2V?/(V? + V?)
D. 2V?/(V? + V?)
Answer : C

43. 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

44. The reference fuels for knock rating of spark ignition engines would include
A. Iso-octane and alpha-methyl naphthalene
B. Normal octane and aniline
C. Isooctane and normal hexane
D. Normal heptane and isooctane
Answer : D

45. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the
A. Exhaust will be smoky
B. Piston rings would stick into piston grooves
C. Engine starts overheating
D. Scavenging occurs
Answer : D

46. 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

47. In petrol engines, advancing of the spark timing will _________ the knocking tendency.
A. Not effect
B. Decrease
C. Increase
D. None of these
Answer : C

48. The ignition of the charge by some hot surface within the engine before the passage of spark is called
A. Pre-ignition
B. Detonation
C. Ignition delay
D. Auto-ignition
Answer : A

49. In compression ignition engines, swirl denotes a
A. Haphazard motion of the gases in the chamber
B. Rotary motion of the gases in the chamber
C. Radial motion of the gases in the chamber
D. None of the above
Answer : B

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