I.C Engines Objective Questions with Answers – Set 09

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Q1. Iso-octane (C₈H₁₈) has octane number of

(A) 0
(B) 50
(C) 100
(D) 120

Answer: (C) 100


Q2. Which is more viscous lube oil?

(A) SEA 30
(B) SAE 50
(C) SAE 70
(D) SAE 80

Answer: (D) SAE 80


Q3. 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) F.P. = I.P. – B.P.


Q4. 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) 90-130 kg/cm²


Q5. 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) More difficult to ignite


Q6. 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) Low heat value


Q7. A carburettor is used to supply

(A) Petrol, air and lubricating oil
(B) Air and diesel
(C) Petrol and lubricating oil
(D) Petrol and air

Answer: (D) Petrol and air


Q8. The two reference fuels used for cetane rating are

(A) Cetane and iso-octane
(B) Cetane and alpha-methyl naphthalene
(C) Cetane and normal heptane
(D) Cetane and tetra ethyl lead

Answer: (B) Cetane and alpha-methyl naphthalene


Q9. The _ engines can work on very lean mixture of fuel.

(A) Spark ignition
(B) Compression ignition
(C) Both (A) and (B)
(D) None of these

Answer: (B) Compression ignition


Q10. The specific fuel consumption per B.P. hour for a diesel engine is about

(A) 0.2 kg
(B) 0.25 kg
(C) 0.3 kg
(D) 0.35 kg

Answer: (A) 0.2 kg


Q11. In a typical medium speed, 4-stroke cycle diesel engine

(A) Fuel injection starts at 10° before top dead center and ends at 20° after top 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) Fuel injection starts at 10° before top dead center and ends at 20° after top dead center


Q12. The knocking in spark ignition engines can be reduced by

(A) Retarding the spark
(B) Increasing the engine speed
(C) Both (A) and (B)
(D) None of these

Answer: (C) Both (A) and (B)


Q13. 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) 2400 km/h


Q14. 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) 180°C


Q15. 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) Indicated power


Q16. 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) Air used for forcing burnt gases out of engine’s cylinder during the exhaust period


Q17. 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) Longer ignition delay


Q18. 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) Rate of rise of pressure


Q19. In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _ the knocking tendency.

(A) Not effected
(B) Decrease
(C) Increase
(D) None of these

Answer: (C) Increase


Q20. The following volume of air is required for consuming 1 liter of fuel by a four stroke engine

(A) 1 m3
(B) 5 m3
(C) 56 m3
(D) 910 m3

Answer: (D) 910 m3


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