Practice Test: Question Set - 10
1. Air fuel ratio at which a petrol engine cannot work is
- (A) 8 : 1
- (B) 10 : 1
- (C) 15 : 1
- (D) 20 : 1 and less
2. 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
3. An hmh flame speed is obtained in diesel engine when air fuel ratio is
- (A) Uniform throughout
the mixture
- (B) Chemically correct
mixture
- (C) About 35% of rich
mixture
- (D) About 10% of rich
mixture
4. A supercharged engine as compared to an ordinary engine
- (A) Is
lighter
- (B) Requires
smaller foundations
- (C) Consumes
less lubricating oil
- (D) All
of these
5. The inlet value of a four stroke cycle I.C engine remains open for nearly
- (A) 180°
- (B) 125°
- (C) 235°
- (D) 200°
6. The basic requirement of a good combustion chamber is
- (A) Minimum
turbulence
- (B) Low
compression ratio
- (C) High
thermal efficiency and power output
- (D) Low
volumetric efficiency
7. The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at
- (A) 1500 rpm
- (B) 750 rpm
- (C) 3000 rpm
- (D) Any value independent
of engine speed
8. In a four stroke cycle petrol engine, the inlet valve
- (A) Opens
at top dead center and closes at bottom dead center
- (B) Opens
at 20° before top dead center and closes at 40° after bottom dead center
- (C) Opens
at 20° after top dead center and closes at 20° before bottom dead center
- (D) May
open or close anywhere
9. Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows
- (A) Using additives in
the fuel
- (B) Increasing the
compression ratio
- (C) Adherence to proper
fuel specification
- (D) Avoidance of
overloading
10. 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.
11. 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
12. 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
13. A diesel engine has
- (A) 1 valve
- (B) 2 valves
- (C) 3 valves
- (D) 4 valves
14. The mechanical efficiency (ηm) of the engine is given by
- (A) ηm = B.P/I.P
- (B) ηm = I.P/B.P
- (C) ηm = (B.P × I.P)/100
- (D) None
of these
15. The output of a diesel engine can be increased without increasing the engine revolution or size in following way
- (A) Feeding more fuel
- (B) Heating incoming air
- (C) Scavenging
- (D) Supercharging
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