I.C Engines Objective Questions with Answers – Set 10

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Q1. 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) Octane number 65


Q2. The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is

(A) Same
(B) More
(C) Less
(D) Less or more depending on operating conditions

Answer: (B) More


Q3. The knocking tendency in spark ignition engines may be decreased by

(A) Controlling the air-fuel mixture
(B) Controlling the ignition timing
(C) Controlling the exhaust temperature
(D) Reducing the compression ratio

Answer: (D) Reducing the compression ratio


Q4. Morse test can be conducted for

(A) Petrol engines
(B) Diesel engines
(C) Multi cylinder engines
(D) All of these

Answer: (C) Multi cylinder engines


Q5. 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) 0.002 second


Q6. A diesel engine, during suction stroke, draws

(A) Air only
(B) Diesel only
(C) A mixture of diesel and air
(D) None of these

Answer: (A) Air only


Q7. The injection pressure in a diesel engine is about

(A) 10 bar
(B) 100 bar
(C) 150 bar
(D) 500 bar

Answer: (B) 100 bar


Q8. 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) 30 kW four-stroke petrol engine running at 1500 r.p.m.


Q9. 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) m.e.p. and I.H.P.


Q10. 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) Relative efficiency


Q11. 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) Less than


Q12. In loop scavenging, the top of the piston is

(A) Flat
(B) Contoured
(C) Slanted
(D) Depressed

Answer: (B) Contoured


Q13. 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) Iso-octane and normal hexane
(D) Normal heptane and iso-octane

Answer: (D) Normal heptane and iso-octane


Q14. 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) 1000°C


Q15. 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) Double


Q16. Fuel oil consumption guarantees for I .C. engine are usually based on

(A) Low heat value of oil
(B) High heat value of oil
(C) Net calorific value of oil
(D) Calorific value of fuel

Answer: (B) High heat value of oil


Q17. 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) Qualitative governing


Q18. The term scavenging is generally associated with

(A) 2-stroke cycle engines
(B) 4-stroke cycle engines
(C) Aeroplane engines
(D) High efficiency engines

Answer: (D) High efficiency engines


Q19. High speed compression engines operate on

(A) Otto cycle
(B) Diesel cycle
(C) Dual combustion cycle
(D) All of these

Answer: (C) Dual combustion cycle


Q20. Which of the following is the lightest and most volatile liquid fuel?

(A) Diesel
(B) Kerosene
(C) Fuel oil
(D) Gasoline

Answer: (D) Gasoline


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