Practice Test: Question Set - 03
1. Crankcase explosion in I.C. engines usually occurs as
- (A) First a mild
explosion followed by a bi explosion
- (B) First a big explosion
followed by a mil explosion
- (C) Both mild and big
explosions occurs simultaneously
- (D) Never occurs
2. The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is
- (A) More
- (B) Less
- (C) Same
- (D) May be more or less
depending on engine capacity
3. In a four stroke cycle diesel engine, the compression
- (A) Starts
at 40° after bottom dead center and ends at 10° before top dead center
- (B) Starts
at 40° before top dead center and ends at 40° after top dead center
- (C) Starts
at top dead center and ends at 40° before bottom dead center
- (D) May start
and end anywhere
4. It the temperature of intake air in IC engines is lowered, then its efficiency will
- (A) Increase
- (B) Decrease
- (C) Remain same
- (D) Increase up to
certain limit and then decrease
5. The loud pulsating noise heard within the cylinder of an internal combustion engine is known as
- (A) Detonation
- (B) Turbulence
- (C) Pre-ignition
- (D) Supercharging
6. Which of the following medium is compressed in a Diesel engine cylinder?
- (A) Air alone
- (B) Air and fuel
- (C) Air and lub oil
- (D) Fuel alone
7. Detonation is harmful due to
- (A) Increase in
the rate of heat transfer, there is a reduction in the power output and
efficiency of the engine
- (B) Excessive
turbulence which removes most of the insulating gas boundary layer from the
cylinder walls
- (C) High
intensity of knock causes crankshaft vibration and the engine runs rough
- (D) None of the
above
8. A stoichiometric air-fuel ratio is
- (A) Chemically correct
mixture
- (B) Lean mixture
- (C) Rich mixture for
idling
- (D) Rich mixture for over
loads
9. The firing order in an I.C. engine depends upon
- (A) Arrangement
of the cylinders
- (B) Design
of crankshaft
- (C) Number
of cylinders
- (D) All of these
10. Pick up the false statement
- (A) Thermal efficiency of diesel engine is
about 34%
- (B) Theoretically correct
mixture of air and petrol is approximately 15:1
- (C) High speed compression engines operate on
dual combustion cycle
- (D) S.I. engines are
quality governed engines
11. 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
12. 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
13. The inlet valve of a four stroke cycle internal combustion engine remains open for
- (A) 130°
- (B) 180°
- (C) 230°
- (D) 270°
14. The minimum cranking speed in case of petrol engine is about
- (A) Half the operating
speed
- (B) One fourth of
operating speed
- (C) 250 - 300 rpm
- (D) 60 - 80 rpm
15. Number of working strokes per min. for a two stroke cycle engine is _________ the speed of the engine in r.p.m.
- (A) Equal to
- (B) One-half
- (C) Twice
- (D) Four-times
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