240 Important Internal Combustion Engines MCQ Question and Answer | PDF Free Download
1.The theoretically correct mixture of air and petrol is
- A10 : 1
- B15 : 1
- C20 : 1
- D25 : 1
2.Polymerization is a chemical process in which molecules of a compound become
- ALarger
- BSlowed down
- CSmaller
- DLiquid
3.The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at
- A1500 rpm
- B750 rpm
- C3000 rpm
- DAny value independent of engine speed
4.During idling, a petrol engine requires _________ mixture.
- ALean
- BRich
- CChemically correct
- DNone of these
5.The increase in intake temperature of internal combustion engines will _________ efficiency.
- AHave no effect on
- BIncrease
- CDecrease
- DNone of these
6.The two reference fuels used for cetane rating are
- ACetane and iso-octane
- BCetane and alpha-methyl naphthalene
- CCetane and normal heptanes
- DCetane and tetra ethyl lead
7.For the same power developed in I.C. engines, the cheaper system is
- ANaturally aspirated
- BSupercharged
- CCentrifugal pump
- DTurbo charger
8.As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
- AIncrease maximum pressure and maximum temperature
- BReduce maximum pressure and maximum temperature
- CIncrease maximum pressure and decrease maximum temperature
- DDecrease maximum pressure and increase maximum temperature
9.The expansion of fuel in a four stroke cycle diesel engine
- AStarts at 15° before top dead center and ends at 30° after top dead center
- BStarts at top dead center and ends at 30° after top dead center
- CStarts at 15° after top dead center and ends at 30° before bottom dead center
- DMay start and end anywhere
10.The fuel valve in a four stroke cycle diesel engine
- AOpens at 15° after top dead center and closes at 20° before bottom dead center
- BOpens at 15° before top dead center and closes at 20° after top dead center
- COpens at top dead center and closes at bottom dead center
- DMay open and close anywhere
11.In a coil ignition system of petrol engines, a condenser is connected across the contact breaker in order to
- APrevent sparking across the gap between the points
- BCause more rapid break of the primary current, giving a higher voltage in the secondary circuit
- CBoth (A) and (B)
- DNone of the above
12.The fuel in diesel engine is normally injected at pressure of
- A5-10 kg/cm²
- B20-25 kg/cm²
- C60-80 kg/cm²
- D90-130 kg/cm²
13.The self ignition temperature of petrol is _________ as compared to diesel oil.
- ASame
- BLower
- CHigher
- DNone of these
14.Which of the following statement is correct?
- ACompression ratio for petrol engines varies from 6 to 10
- BHigher compression ratio in diesel engines results in higher pressures
- CPetrol engines work on Otto cycle
- DAll of the above
15.The air standard efficiency of an I.C. engine depends on
- AFuel used
- BSpeed of engine
- CCompression ratio
- DNone of these
16.In a typical medium speed 4-stroke cycle diesel engine
- ACompression starts at 35° after bottom dead center and ends at top dead center
- BCompression starts at bottom dead center and ends at top dead center
- CCompression starts at 10° before bottom dead center and, ends just before top dead center
- DMay start and end anywhere
17.The exhaust valve in a four stroke cycle petrol engine
- AOpens at 50° before bottom dead center and closes at 15° after top dead center
- BOpens at bottom dead center and closes at top dead center
- COpens at 50° after bottom dead center and closes at 15° before top dead center
- DMay open and close anywhere
18.For the same compression ratio
- AOtto cycle is more efficient than the Diesel
- BDiesel cycle is more efficient than Otto
- CBoth Otto and Diesel cycles are, equally efficient
- DCompression ratio has nothing to do with efficiency
19.The ratio of the brake power to the indicated power is called
- AMechanical efficiency
- BOverall efficiency
- COverall efficiency
- DIndicated thermal efficiency
20.Scavenging air in diesel engine means
- AAir used for combustion sent under pressure
- BForced air for cooling cylinder
- CBurnt air containing products of combustion
- DAir used for forcing burnt gases out of engine's cylinder during the exhaust period