Refrigeration And Air Conditioning Set 8 MCQs

Q1 | In order to ensure leak proof mechanical links, the end of copper tubing in refrigeration cycle is

Flared

Brazed

Soldered

Press-fitted

(C) and (D) together

Q2 | A Bell-Coleman cycle is

Reversed Otto cycle

Reversed Carnot cycle

Reversed Sterling cycle

Reversed Joule cycle

Reversed Rankine cycle

Q3 | On a particular time of a day if dry bulb temperature is equal to the wet bulb temperature, then it can be safely concluded that

Dew point was less than 20?C

Rain had occurred one or two hours earlier

Relative humidity of air was 100%

Specific humidity of air was 0.010 kg per kg of dry air

Atmospheric air was free from moisture

Q4 | Which of the following is not a dehydrator?

Silica sel

Molecular sieve

Calcium chloride

Sodium chloride

All of the above

Q5 | A water cooler is installed with one ton vapour compression cycle. In 24 hours it will provide

0.1 ton of cold water

One tonne of cold water

The change is gradual throughout the cycle

More than one tonne of cold water

Half ton of cold water

Q6 | In rainy season desert coolers become ineffective

Because of low temperature

Pleasant weather

Rain serves the purpose of cooler

Humidity of air increases

None of the above

Q7 | When Freon 12 is the refrigerant, the condenser and evaporator cables are made of

Aluminium

Cast iron

Steel

Copper

Wrought iron

Q8 | In vapour absorption system using ammonia, water is required for

Absorber only

Separator only

Condenser, absorber and separator

Condenser only

Condenser and absorber

Q9 | The ratio of mass of water vapour associated with unit mass of dry air to the mass of water vapour associated with unit mass of dry air saturated at the same temperature is known as

Relative humidity

Specific humidity decreases

Humidity ratio

Degree of saturation

None of the above

Q10 | In a refrigerator system if compressor fails to operate, the probable reason could be

Power failure

Low voltage

Burnt motor

Fuse blown

Any of the above

Q11 | A thermometer in vapour compression system is installed in the main line close to the compressor

As it helps the operator to adjust compressor for greatest efficiency

As temperature indicates whether liquid or vapour refrigerant is going to compressor

As temperature helps in calculating the coefficient of performance

As the performance of other units of the cycle can be controlled

None of the above

Q12 | White ice is

Sub-cooled water

Fast cooled water

Due to dissolved air, gases and impurities

Produced by blowing air during freezing

None of the above

Q13 | In which type of single phase motor the starting torque is low

Capacitor start type

Shaded pole type

Starting torque is same in all motors

Permanent split capacitor type

Capacitor start and capacitor run type

Q14 | Air conditioning means

All above

Removal of air impurities

Heating

Dehumidifying

Cooling

Q15 | Dew points temperature is an indication of

Moisture content of air

Dryness of air

Lowest temperature where air and water vapour start separating

Condition air

Any of the above

Q16 | The most common type of vapour absorption system in use for industrial application is

Hydrogen and water

Freon 22 and water

Brine and water

Freon 12 and water

Ammonia and water

Q17 | Brazing is the process used for joining

Two ferrous materials

One ferrous and one non-ferrous material

Two non-ferrous materials

Two non-metals

None of the above

Q18 | Of the following chemicals the liquid having the greatest cooling effect on an individual is

Water

Water containing ammonium hydroxide

Ether

Alcohol

Brine

Q19 | In vapour absorption system the function of rectifier is

To cool the vapour leaving the analyzer

To separate ammonia and water

To dissolve ammonia in water

To add energy from external source

None of the above

Q20 | Sometimes refrigeration plants use cooling towers. The water cooled in those towers is supplied

For defrosting evaporator coils

To cool compressor cylinder only

To cool refrigerant in evaporator

To cool refrigerant in condenser

None of the above

Q21 | When moisture is added to air at constant dry bulb temperature, the process is known as

Humidification

Sensible cooling

Wetting

Chilling

None of the above

Q22 | The condition of refrigerant before and after the condenser in a vapour compression cycle is

Wet vapour, wet vapour

Dry saturated, wet vapour

Dry saturated, dry saturated

Liquid, liquid

Dry saturated, saturated liquid

Q23 | The COP of a reversed Carnot cycle is 5. The ratio of highest absolute temperature to the lowest absolute temperature

0.8

1.2

0.2

1.25

5

Q24 | In case the relative humidity of atmospheric air is 100% the rate of evaporation of water will be

Half the water already air

Very high

Zero

Slow

Half the water already air

Q25 | In which of the following plants secondary refrigerant is used?

Domestic refrigerator

Room air conditioner

Deep freezer

Ice plant

None of the above