1000+ Internal Combustion MCQ for CLAT PG [Solved]

1. 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

2. 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

3. Supercharging is essential in
A. Diesel engines
B. Gas turbines
C. Petrol engines
D. Aircraft engines
Answer : D

4. 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

5. The normal heptane (C₇H₁₆) is given a rating of ________ octane number.
A. 0
B. 50
C. 100
D. 120
Answer : A

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

7. 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

8. 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

9. The combustion in compression ignition engines is
A. Homogeneous
B. Heterogeneous
C. Both (A) and (B)
D. None of these
Answer : B

10. Which of the following fuel has little tendency towards detonation?
A. Benzene
B. Iso-octane
C. Normal heptane
D. Alcohol
Answer : B

11. 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

12. Supercharging is the process of supplying the intake air to the engine cylinder at a density _________ the density of the surrounding atmosphere.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C

13. 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

14. 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

15. 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

16. Which one of the following engines will have heavier flywheel than the remaining ones?
A. 30 kW four-stroke petrol engine running at 1500 r.p.m.
B. 30 kW two-stroke petrol engine running at 1500 r.p.m.
C. 30 kW two-stroke diesel engine running at 750 r.p.m.
D. 30 kW four-stroke diesel engine running at 750 r.p.m.
Answer : A

17. In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
A. Fuel pump
B. Fuel injector
C. Spark plug
D. None of these
Answer : C

18. 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

19. The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency.
A. Increase
B. Reduce
C. Not effect
D. None of these
Answer : B

20. As a result of detonation in an I.C. engine, following parameter attains very high value
A. Peak pressure
B. Rate of rise of pressure
C. Rate of rise of temperature
D. Peak temperature
Answer : B

21. Alpha-methyl-naphthalene (C?? H??) has a cetane number of
A. 0
B. 50
C. 100
D. 120
Answer : A

22. 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

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

24. 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

25. 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

26. 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

27. The ignition quality of diesel oil is expressed by
A. Cetane number
B. Octane number
C. Calorific value
D. None of these
Answer : A

28. 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

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

30. The advancing of spark timing in spark ignition engines will _________ knocking tendency.
A. Increase
B. Reduce
C. Not effect
D. None of these
Answer : A

31. High speed compression engines operate on
A. Otto cycle
B. Diesel cycle
C. Dual combustion cycle
D. All of these
Answer : C

32. 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

33. The sensing element in the control system of nuclear reactors measures the _________ of the neutron flux in the reactor.
A. Temperature
B. Volume
C. Density
D. None of these
Answer : C

34. 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

35. 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

36. In a four stroke cycle petrol engine, the compression
A. Starts at 40° after bottom dead centre and ends at 30° before top dead centre
B. Starts at 40° before bottom dead centre and ends at 30° after bottom dead centre
C. Starts at bottom dead centre and ends at top dead centre
D. May start and end anywhere
Answer : A

37. 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

38. 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

39. 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

40. 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

41. Gaseous fuel guarantees are based on
A. Calorific value of oil
B. Low heat value of oil
C. High heat value of oil
D. Mean heat value of oil
Answer : B

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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

48. 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

49. The mean effective pressure obtained from engine indicator indicates the
A. Maximum pressure developed
B. Minimum pressure
C. Instantaneous pressure at any instant
D. Average pressure
Answer : D

50. 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