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Current Affairs January 2024

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4

Polymerisation is a chemical process in which molecules of a compound become

A. Larger

B. Slowed down

C. Smaller

D. Liquid

Correct Answer :

A. Larger


Related Questions

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4

Which of the following statement is correct regarding petrol engines?

A. A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure

B. The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug

C. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition

D. All of the above

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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

A supercharged engine as compared to an ordinary engine

A. Requires smaller foundation

B. Is lighter

C. Consumes less lubricating oil

D. All of these

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4

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

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4

The voltage required to produce a spark across the gap, between the sparking points is

A. 2000 to 4000 volts

B. 4000 to 6000 volts

C. 6000 to 10,000 volts

D. 10,000 to 12,000 volts

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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 turbine of the turboprop engine is __________ that of the turbojet engine.

A. Same as

B. Smaller than

C. Bigger than

D. None of these

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4

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

A. Supercharging

B. Carburetion

C. Turbulence

D. Delay period

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4

Most high speed compression engines operate on

A. Diesel cycle

B. Otto cycle

C. Dual combustion cycle

D. Special type of air cycle

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4

If the speed of the engine is increased, the indicated power will

A. Increase

B. Decrease

C. Remain same

D. None of these

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4

In diesel engine, the compression ratio in comparison to expansion ratio is

A. Same

B. Less

C. More

D. Variable

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4

A diesel engine has

A. One valve

B. Two valves

C. Three valves

D. Four valves

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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

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

The cetane number of diesel oil, generally available, is

A. 20 to 25

B. 25 to 30

C. 30 to 40

D. 40 to 55

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4

A diesel engine, during suction stroke, draws

A. Air only

B. Diesel only

C. A mixture of diesel and air

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

All heat engines utilize

A. Low heat value of oil

B. High heat value of oil

C. Net calorific value of oil

D. Calorific value of fuel

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4

The combustion in compression ignition engines is

A. Homogeneous

B. Heterogeneous

C. Both (A) and (B)

D. None of these

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4

The volumetric efficiency of a well designed engine may be

A. 30 to 40 %

B. 40 to 60 %

C. 60 to 70 %

D. 75 to 90 %

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4

In a four stroke cycle diesel engine, the inlet valve

A. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

B. Opens at 20° after top dead centre and closes at 20° before bottom dead centre

C. Opens at top dead centre and closes at bottom dead centre

D. May open and close anywhere

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4

Which of the following statements is correct?

A. All the irreversible engines have same efficiency

B. All the reversible engines have same efficiency

C. Both Rankine and Carnot cycles have same efficiency between same temperature limits

D. All reversible engines working between same temperature limits have same efficiency

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4

The reason for supercharging in any engine is to

A. Increase efficiency

B. Increase power

C. Reduce weight and bulk for a given output

D. Effect fuel economy

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4

Antiknock for compression ignition engines is

A. Napthene

B. Tetra ethyl lead

C. Amyl nitrate

D. Hexadecane

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4

In a four stroke cycle petrol engine, the charge is ignited at

A. 30° before top dead centre

B. 30° after top dead centre

C. 30° before bottom dead centre

D. 30° after bottom dead centre

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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

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

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4

The air-fuel ratio in petrol engines is controlled by

A. Controlling valve opening/closing

B. Governing

C. Injection

D. Carburetion

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4

High speed compression engines operate on

A. Otto cycle

B. Diesel cycle

C. Dual combustion cycle

D. All of these

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4

A fuel of cetane number 40 has the same ignition quality as a mixture of

A. 40% cetane and 60% alpha methyl naphthalene

B. 40% alpha methyl naphthalene and 60% cetane

C. 40% petrol and 60% diesel

D. 40% diesel and 60% petrol