Internal Combustion 1000+ MCQ with answer for SSC Stenographer

1. 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

2. Volatility of diesel fuel oil is
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 : D

3. 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

4. Morse test is used to determine the I.P. of a
A. Single cylinder petrol engine
B. Four stroke engine
C. Single cylinder diesel engine
D. Multi cylinder engine
Answer : D

5. The scavenging efficiency of a four stroke cycle diesel engine is
A. Below 50%
B. Between 50 and 85%
C. Between 85 and 95%
D. Between 95 and 100%
Answer : D

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

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. 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

9. 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

10. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
A. Net efficiency
B. Efficiency ratio
C. Relative efficiency
D. Overall efficiency
Answer : C

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 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

13. 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

14. 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

15. Which of the following fuel detonates readily?
A. Benzene
B. Iso-octane
C. Normal heptane
D. Alcohol
Answer : C

16. In a typical medium speed 4-stroke cycle diesel engine
A. Compression starts at 35° after bottom dead center and ends at top dead center
B. Compression starts at bottom dead center and ends at top dead center
C. Compression starts at 10° before bottom dead center and, ends just before top dead center
D. May start and end anywhere
Answer : A

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

18. 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

19. 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

20. During idling, a petrol engine requires _________ mixture.
A. Lean
B. Rich
C. Chemically correct
D. None of these
Answer : B

21. 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

22. The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
A. Not effect
B. Decrease
C. Increase
D. None of these
Answer : C

23. Pick up the wrong statement
A. 2-stroke engine can run in any direction
B. In 4-stroke engine, a power stroke is obtained in 4-strokes
C. Thermal efficiency of 4-stroke engine is more due to positive scavenging
D. Petrol engines occupy more space than diesel engines for same power output
Answer : D

24. The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed
A. 80°C
B. 120°C
C. 180°C
D. 240°C
Answer : C

25. The injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to
A. Inject fuel in a chamber of high pressure at the end of compression stroke
B. Inject fuel at a high velocity to facilitate atomisation
C. Ensure that penetration is not high
D. All of the above
Answer : D

26. 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

27. 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

28. 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

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

30. 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

31. Installation of supercharger on a four cycle diesel engine can result in the following percentage increase in power
A. Up to 35%
B. Up to 50%
C. Up to 75%
D. Up to 100%
Answer : D

32. 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

33. Which of the following statement is correct regarding normal cetane?
A. It is a standard fuel used for knock rating of diesel engines
B. Its chemical name is normal hexadecane
C. It has long carbon chain structure
D. All of the above
Answer : D

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

35. 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

36. The ignition quality of petrol is expressed by
A. Cetane number
B. Octane number
C. Calorific value
D. All of these
Answer : B

37. 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

38. In a four stroke cycle engine, the sequence of operations is
A. Suction, compression, expansion and exhaust
B. Suction, expansion, compression and exhaust
C. Expansion, compression, suction and exhaust
D. Compression, expansion, suction and exhaust
Answer : A

39. The thermal efficiency of petrol and gas engines is about
A. 15 %
B. 30 %
C. 50 %
D. 70 %
Answer : B

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

41. 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

42. 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

43. 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

44. 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

45. 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

46. Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following
A. Piston ring and cylinder wear
B. Formation of hard coating on piston skirts
C. Oil sludge in the engine crank case
D. Detonation
Answer : D

47. 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

48. In the opposed piston diesel engine, the combustion chamber is located
A. Above the piston
B. Below the piston
C. Between the pistons
D. There is no such criterion
Answer : C

49. 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

50. The fuels in order of decreasing knock tendency for spark ignition engines are
A. Paraffin, aromatic, napthene
B. Paraffin, napthene, aromatic
C. Napthene, aromatics, paraffin
D. Napthene, paraffin, aromatic
Answer : B