I.C Engines (Multiple Choice Questions) with Answers-Quiz with answers for Mechanical jobs interviews and competitive exam
1.
The maximum temperature in the I.C. engine
cylinder is of the order of-
a)
500- 1000°C
b)
1000- 1500°C
c)
1500-2000°C
d) 2000-2500°C
2.
Thermal efficiency of a diesel cycle having
fixed compression ratio, with an increase in the cut-off ratio will
a)
increase
b) decrease
c)
be independent
d)
may increase or decrease depending on other
factors
3.
Pick up the wrong statement
a)
2-stroke engine can run in any direction
b) petrol engines occupy more space than
diesel engines for same power output.
c)
thermal efficiency of 4-stroke engine is more
due to positive scavenging
d)
petrol engines work on otto cycle
4.
Combustion in compression ignition engines is
a)
homogeneous
b) heterogeneous
c)
both (a) and (b)
d)
laminar
5.
The fuel in diesel engine is normally injected
at pressure of-
a)
5-l0 kg/cm2
b)
20-25 kg/cm2
c)
60-80 kg/cm2
d) 90-130 kg/cm2
6.
The specific fuel consumption per BHP hour for
diesel engine is approximately
a)
0.15 kg
b) 0.2 kg
c)
0.25 kg
d)
0.3 kg
7.
The temperature of interior surface of cylinder
wall in normal operation is not allowed to exceed-
a)
80°C
b)
120°C
c) 180°C
d)
240°C
8.
Crankcase explosion ¡n IC. 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 simultaneously
d)
never occurs
9.
Compression loss in l.C engines occurs due to
a)
leaking piston rings
b)
use of thick head gasket
c)
clogged air-inlet slots
d) all of the above
10.
The specific fuel consumption per BH hour for a
petrol engine is approximately-
a)
0.15 kg
b)
0.2 kg
c) 0.25 kg
d)
0.3kg
11.
The air requirement of a petrol engine during
starting compared to theoretical air required for complete combustion is
a)
more
b) loss
c)
same
d)
may be more or less depending on engine capacity
12.
The inlet value of a four stroke cycle l.C
engine remains open for nearly
a)
1800
b)
125°
c) 235°
d)
200°
13.
Which of the following is not an interns
combustion engine
a)
2-stroke petrol engine
b)
4-stroke petrol engine
c)
diesel engine
d) steam turbine
14.
Pick up the false statement-
a)
Thermal efficiency of diesel engine is about 34%
b)
Theoretically correct mixture of air am petrol
is approximately 15 : 1
c)
High speed compression engines operate on dual
combustion cycle
d) S.l engines are quality-governed engines
15.
If one cylinder of a diesel engine receives more
fuel than the others, then for that cylinder the
a)
exhaust will be smoky
b)
piston rings would stick into piston grooves
c)
exhaust temperature will be high
d) scavenging occurs
16.
The output of a diesel engine can be increased
without increasing the engine revolution or size in following way
a)
feeding more fuel
b) supercharging.
c)
heating incoming air
d)
scavenging
17.
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
18.
The process of breaking up or a liquid into fine
droplets by spraying ¡s called
a)
vaporization
b)
atomization.
c)
ionization
d)
injection
19.
As a result of detonation in an l.C. engine,
following parameter attains very high value
a)
peak pressure
b) rate of rise of pressure
c)
rate of rise of temperature
d)
peak temperature
20.
Most high speed compression engines operate on
a)
Diesel cycle
b)
Otto cycle
c) Dual combustion cycle
d)
Special type of air cycle
21.
The accumulation of carbon in a cylinder results
in increase of-
a)
clearance volume
b)
volumetric efficiency
c)
ignition time
d) effective compression ratio
22.
The air-fuel ratio of the petrol engine is
controlled by
a)
fuel pump
b)
governor
c)
injector
d) carburetor
23.
In a typical medium speed, 4-stroke cycle diesel
engine
a) Fuel injection starts at 100 before to dead
center and ends at 20° after tor dead center
b)
fuel injection starts at top dead center and
ends at 20° after top dead center
c)
fuel injection starts at just before top dead
center and ends just after top deaf center
d)
may start and end anywhere
24.
Diesel fuel, compared to petrol is
a)
less difficult to ignite
b)
just about the same difficult to ignite
c) more difficult to ignite
d)
highly ignitable
25.
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)
15OCPC
26.
The rating of a diesel engine, with increase in
air inlet temperature, will
a)
increase linearly
b) decrease linearly
c)
increase parabolically
d)
decrease parabolically
27.
A 75 cc engine has following parameter as 75 cc
a)
fuel tank capacity
b)
lub oil capacity
c) swept volume
d)
cylinder volume
28.
A heat engine utilizes the
a)
calorific value of oil
b)
low heat value of
c) high heat value of oil
d)
mean heat value of oil
29.
Gaseous-fuel guarantees are based on
a)
calorific value of oil
b) low heat value of oil
c)
high heat value of oil
d)
mean heat value of oil
30.
Polymerizations is a chemical process in which
molecules of a compound become
a) larger
b)
slowed down
c)
smaller
d)
liquid
31.
The term scavenging is generally associated with
a)
2-stroke cycle engines
b)
4-stroke cycle engines
c)
aero plane engines
d) high efficiency engines
32.
In diesel engine, the compression ratio in comparison
to expansion ratio ¡s
a)
same
b)
less
c) more
d)
variable
33.
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
34.
Engine pistons ‘are usually made of aluminium
alloy because it
a) is lighter
b)
wears less
c)
absorbs shocks
d)
¡s stronger
35.
Most high speed compression engines operate on
a)
Otto cycle
b)
Diesel cycle
c) Dual cycle
d)
Carnot cycle
36.
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
37.
The size of inlet valve of.an engine in
comparison to exhaust valve is-
a)
more
b) less
c)
same
d)
more/less depending on capacity of engine
38.
In a cycle, the spark lasts roughly for-
a)
1 sec
b)
0.1 sec
c)
0.01 sec
d) 0.001 sec
39.
Air fuel ratio for idling speed of a petrol
engine is approximately
a)
1: 1
b)
5:1
c) 10:1
d)
15 : 1