Practice Internal Combustion Engines (I.C. Engines) Multiple Choice Questions Quiz-4 - MCQGeeks.com

Q.1

The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called

Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency

Q.2

Which of the following statements is correct?

All the irreversible engines have same efficiency
All the reversible engines have same efficiency
Both Rankine and Carnot cycles have same efficiency between same temperature limits
All reversible engines working between same temperature limits have same efficiency

Q.3

The specific fuel consumption per B.P. hour for a diesel engine is about

0.2 kg
0.25 kg
0.3 kg
0.35 kg

Q.4

The ignition quality of petrol is expressed by

Cetane number
Octane number
Calorific value
All of these

Q.5

The ignition quality of diesel oil is expressed by

Cetane number
Octane number
Calorific value
None of these

Q.6

A 5 BHP engine running at full load would consume diesel of the order of

0.3 kg/hr
1 kg/hr
3 kg/hr
5 kg/hr

Q.7

In a cycle, the spark lasts roughly for

1 sec
0.1 sec
0.01 sec
0.001 sec

Q.8

Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to

Cylinder walls being too hot
Overheated spark plug points
Red hot carbon deposits on cylinder walls
Any one of these

Q.9

If the compression ratio in I.C. engine increases, then its thermal efficiency will

Decrease
Increase
Remain same
None of these

Q.10

The minimum cranking speed in case of petrol engine is about

Half the operating speed
One fourth of operating speed
250 - 300 rpm
60 - 80 rpm

Q.11

The injection pressure in a diesel engine is about

10 bar
100 bar
150 bar
500 bar

Q.12

The specific fuel consumption per B.P. hour for a petrol engine is about

0.2 kg
0.25 kg
0.3 kg
0.35 kg

Q.13

Supercharging is the process of

Supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
Providing forced cooling air
Injecting excess fuel for raising more loads
Supplying compressed air to remove combustion products fully

Q.14

A carburettor is used to supply

Petrol, air and lubricating oil
Air and diesel
Petrol and lubricating oil
Petrol and air

Q.15

The fuels in order of decreasing knock tendency for spark ignition engines are

Paraffin, aromatic, napthene
Paraffin, napthene, aromatic
Napthene, aromatics, paraffin
Napthene, paraffin, aromatic

Q.16

The knocking tendency in compression ignition engines for a given fuel will be

Enhanced by decreasing compression ratio
Enhanced by increasing compression ratio
Dependent on other factors
None of the above

Q.17

Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows

Using additives in the fuel
Increasing the compression ratio
Adherence to proper fuel specification
Avoidance of overloading

Q.18

In a naturally aspirated diesel engine, the air is supplied by

A supercharger
A centrifugal blower
A vacuum chamber
An injection tube

Q.19

In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of

250°C
500°C
1000°C
2000°C

Q.20

Detonation is harmful due to

Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine
Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls
High intensity of knock causes crankshaft vibration and the engine runs rough
None of the above

Q.21

In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a

Fuel pump
Fuel injector
Spark plug
None of these

Q.22

Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of

Plates
Pallets
Pins
All of these

Q.23

The object of supercharging the engine is

To reduce mass of the engine per brake power
To reduce space occupied by the engine
To increase the power output of an engine when greater power is required
All of the above

Q.24

The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be

25%
50%
70%
100%

Q.25

The ratio of the indicated thermal efficiency to the air standard efficiency is known as

Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency

Q.26

The operation of forcing additional air under pressure in the engine cylinder is known as

Scavenging
Turbulence
Supercharging
Pre-ignition

Q.27

Stoichiometric ratio is

Chemically correct air-fuel ratio by weight
Chemically correct air-fuel ratio by volume
Actual air-fuel ratio for maximum efficiency
None of the above

Q.28

Volatility of diesel fuel oil is

Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
Temperature at which it solidifies or congeals
It catches fire without external aid
Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off

Q.29

The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called

Net efficiency
Efficiency ratio
Relative efficiency
Overall efficiency

Q.30

The knock in diesel engine occurs due to

Instantaneous and rapid burning of the first part of the charge
Instantaneous auto ignition of last part of charge
Delayed burning of the first part of the charge
Reduction of delay period

0 h : 0 m : 1 s