I.C Engines Objective Questions with Answers – Set 11

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Q1. 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) All of the above


Q2. The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will

(A) Increase
(B) Decrease
(C) Be independent
(D) May increase or decrease depending on other factors

Answer: (B) Decrease


Q3. 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) More efficient


Q4. Antiknock for compression ignition engines is

(A) Napthene
(B) Tetra ethyl lead
(C) Amyl nitrate
(D) Hexadecane

Answer: (C) Amyl nitrate


Q5. 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) Multi cylinder engine


Q6. 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) Opens at 30° before bottom dead centre and closes at 10° after top dead centre


Q7. The inlet valve of a four stroke cycle internal combustion engine remains open for

(A) 130°
(B) 180°
(C) 230°
(D) 270°

Answer: (C) 230°


Q8. Scavenging is usually done to increase

(A) Thermal efficiency
(B) Speed
(C) Power output
(D) Fuel consumption

Answer: (C) Power output


Q9. 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) Four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine


Q10. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

(A) 1/2
(B) 1
(C) 2
(D) 4

Answer: (C) 2


Q11. A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is

(A) 248 cm3
(B) 252 cm3
(C) 264 cm3
(D) 286 cm3

Answer: (C) 264 cm3


Q12. 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) Effective compression ratio


Q13. 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) Flow is produced due to the static head in the float chamber


Q14. A diesel engine has

(A) 1 valve
(B) 2 valves
(C) 3 valves
(D) 4 valves

Answer: (C) 3 valves


Q15. Theoretically, a four stroke cycle engine should develop _ power as that of a two stroke cycle engine.

(A) Half
(B) Same
(C) Double
(D) Four times

Answer: (A) Half


Q16. 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) Otto cycle is more efficient than the Diesel


Q17. 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) All of the above


Q18. The theoretically correct mixture of air and petrol is

(A) 10 : 1
(B) 15 : 1
(C) 20 : 1
(D) 25 : 1

Answer: (B) 15 : 1


Q19. 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) 10 bar


Q20. The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of

(A) Morse test
(B) Prony brake test
(C) Motoring test
(D) Heat balance test

Answer: (A) Morse test


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