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4

The ignition quality of diesel oil is expressed by

A. Cetane number

B. Octane number

C. Calorific value

D. None of these

Correct Answer :

A. Cetane number


Related Questions

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4

The pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.

A. Equal to

B. Below

C. Above

D. None of these

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4

Which of the following does not relate to a compression ignition engine?

A. Fuel pump

B. Fuel injector

C. Governor

D. Carburettor

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4

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

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4

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

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4

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

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4

In compression ignition engines, swirl denotes a

A. Haphazard motion of the gases in the chamber

B. Rotary motion of the gases in the chamber

C. Radial motion of the gases in the chamber

D. None of the above

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4

Which one of the following engines will have heavier flywheel than the remaining ones?

A. 30 kW four-stroke petrol engine running at 1500 r.p.m.

B. 30 kW two-stroke petrol engine running at 1500 r.p.m.

C. 30 kW two-stroke diesel engine running at 750 r.p.m.

D. 30 kW four-stroke diesel engine running at 750 r.p.m.

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4

A mixture containing 65% of iso-octane and 35% of normal heptane will have

A. Cetane number 65

B. Octane number 65

C. Cetane number 35

D. Octane number 35

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4

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

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4

The probability of knocking in diesel engines is increased by

A. High self ignition temperature

B. Low volatility

C. Higher viscosity

D. All of these

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4

Installation of supercharger on a four cycle diesel engine can result in the following percentage increase in power

A. Up to 35%

B. Up to 50%

C. Up to 75%

D. Up to 100%

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4

The reflectivity depends upon

A. Geometry of the reflector

B. Energy of neutrons

C. Properties of the reflector

D. All of these

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4

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

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4

The pressure at the end of compression, in petrol engines, is approximately

A. 10 bar

B. 20 bar

C. 25 bar

D. 35 bar

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4

The thermal efficiency of petrol and gas engines is about

A. 15 %

B. 30 %

C. 50 %

D. 70 %

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4

The cetane (C16H34) which is a straight chain paraffin, is assigned a cetane number of

A. 0

B. 50

C. 100

D. 120

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4

The following volume of air is required for consuming 1 litre of fuel by a four stroke engine

A. 1 m3

B. 5 m3

C. 56 m3

D. 910 m3

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4

The ratio of the brake power to the indicated power is called

A. Mechanical efficiency

B. Overall efficiency

C. Indicated thermal efficiency

D. Volumetric efficiency

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4

Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads

A. The friction is high

B. The friction is unpredictable

C. The small difference in cooling water temperature or in internal friction has a disproportionate effect

D. The engine is rarely operated

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4

In a typical medium speed 4-stroke cycle diesel engine the inlet valve

A. Opens at 20° before top dead center and closes at 35° after the bottom dead center

B. Opens at top dead center and closes at bottom dead center

C. Opens at 10° after top dead center and closes 20° before the bottom dead center

D. May open or close anywhere

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4

In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then _________ is employed.

A. Fuel pump

B. Injector

C. Carburettor

D. None of these

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4

The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

A. 1/2

B. 1

C. 2

D. 4

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4

Compression loss in I.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

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4

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

A. Scavenging

B. Turbulence

C. Supercharging

D. Pre-ignition

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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

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4

The ignition quality of petrol is expressed by

A. Cetane number

B. Octane number

C. Calorific value

D. All of these

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4

If V₁ is the jet velocity and V₀ is the vehicle velocity, then the propulsive efficiency of a rocket is given by

A. [2(V₀/V₁)]/ [1 + (V₀/V₁)²]

B. (V₀/V₁)/ [1 + (V₀/V₁)²]

C. V₀/(V₀ + V₁)

D. V₁/(V₀ + V₁)

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4

The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the

A. Jet area is automatically varied depending on the suction

B. The flow from the main jet is diverted to the compensating jet with increase in speed

C. The diameter of the jet is constant and the discharge coefficient is invariant

D. Flow is produced due to the static head in the float chamber

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4

In petrol engines, advancing of the spark timing will _________ the knocking tendency.

A. Not effect

B. Decrease

C. Increase

D. None of these

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4

In a four stroke cycle diesel engine, the compression

A. Starts at 40° after bottom dead centre and ends at 10° before top dead centre

B. Starts at 40° before top dead centre and ends at 40° after top dead centre

C. Starts at top dead centre and ends at 40° before bottom dead centre

D. May start and end anywhere