Explore topic-wise MCQs in Refrigeration and Air conditioning.

This section includes 205 Mcqs, each offering curated multiple-choice questions to sharpen your Refrigeration and Air conditioning knowledge and support exam preparation. Choose a topic below to get started.

1.

In a refrigeration system, if the compressor short cycles, the probable cause could be

A. Intermittent contact in electric control circuit
B. Dirty or iced evaporator
C. Lack of refrigerant
D. Overchange of refrigerant
E. Any of the above
Answer» F.
Discussion
2.

As warm air cools, its

A. Relative humidity increases
B. Relative humidity decreases
C. There is no effect on moisture holding capacity
D. Capacity to hold moisture increases
E. Dew point occurs
Answer» C. There is no effect on moisture holding capacity
Discussion
3.

During adiabatic saturation process on unsaturated air

A. Dry bulb temperature remains constant
B. Wet bulb temperature remains constant
C. Dew point temperature remains constant
D. Relative humidity remains constant
E. None of the above
Answer» C. Dew point temperature remains constant
Discussion
4.

Defrosting of evaporators is done because

A. Frosting increases refrigerating effect
B. Frosting retards heat flow
C. Frosting is undersirable
D. Frosting obstructs flow of refrigerant
E. Frosting may cause damage to equipment
Answer» C. Frosting is undersirable
Discussion
5.

Anhydrous substance is

A. Free of hydrogen and other chemicals containing hydrogen
B. Dry substance
C. Free of humidity
D. Free of hydrogen
E. Free of water especially water of crystallization
Answer» F.
Discussion
6.

In a small vapour compression cycle using capillary tubing for expansion, if suddenly uncondensed vapours enter the tubing, the result will be

A. Improved refrigerating capacity
B. Loss in refrigerating capacity
C. Supply of superheated vapour to compressor
D. Choking of drier
E. All of the above
Answer» C. Supply of superheated vapour to compressor
Discussion
7.

Capacity of a domestic refrigerator is in the range

A. 1 to 3 tonnes
B. 7 to 10 tonnes
C. 0.1 to 0.3 tonnes
D. 3 to 5 tonnes
E. 5 to 7 tonnes
Answer» D. 3 to 5 tonnes
Discussion
8.

In cooling towers the heat is dissipated mainly by

A. Freezing
B. Convection
C. Radiation
D. Conduction
E. Evaporation
Answer» F.
Discussion
9.

A Salinometer

A. Measure intensity of illumination
B. Measures temperatures in cryogenic regions
C. Measures solar radiation
D. Measures sound level
E. Measures density of brine
Answer» F.
Discussion
10.

If a one ton refrigeration machine, the significance of term "One ton" is that

A. One ton of water can be converted into ice
B. One ton of ice when melts from and at 0?C in 24 hours the refrigeration effect equivalent to that
C. One ton water can be stored at a time
D. One ton is the total weight of equipment
E. One ton of refrigerant is used
Answer» C. One ton water can be stored at a time
Discussion
11.

No liquid can exist as a liquid at

A. 100?C
B. Zero pressure
C. Zero viscosity
D. 0?C
E. 10,000 m height above the surface of earth
Answer» C. Zero viscosity
Discussion
12.

If a refrigerator is directly exposed to sun rays

A. It will stop working
B. The refrigerant will leak
C. There will be less cooling effect
D. Frost will be formed on cabinet surface
E. (A) and (B) above
Answer» D. Frost will be formed on cabinet surface
Discussion
13.

Water is used as a refrigerant in

A. Vapour absorption cycle
B. Steam jet refrigeration
C. Vapour absorption cycle
D. Cascade system
E. None of the above
Answer» C. Vapour absorption cycle
Discussion
14.

Which of the following valves is used on domestic refrigerators

A. Solenoid valve
B. Expansion valve
C. Spring safety valve
D. Wheel valve
E. None of the above
Answer» F.
Discussion
15.

During dehumidification process

A. Relative humidity decreases
B. Relative humidity does not change
C. Specific humidity decreases
D. Relative humidity increases
E. Specific humidity increases
Answer» B. Relative humidity does not change
Discussion
16.

Dischloromono fluoroethane is

A. Freon 11
B. Freon 12
C. Freon 21
D. Freon 22
E. None of the above
Answer» E. None of the above
Discussion
17.

A condenser removes from the refrigerant

A. Sensible heat only
B. Latent heat only
C. Sensile heat and latent heat
D. Partly sensible heat and latent heat
E. None of the above
Answer» B. Latent heat only
Discussion
18.

In a refrigeration system a condenser

A. Receives liquid refrigerant and supplies liquid refrigerant
B. Receives vapour refrigerant and supplies vapour refrigerant
C. Receives vapour refrigerant and supplies liquid refrigerant
D. Receives liquid refrigerant and supplies liquid refrigerant
E. None of the above
Answer» D. Receives liquid refrigerant and supplies liquid refrigerant
Discussion
19.

The bulk of tubes at the back of the domestic refrigerator are

A. Condenser tubes
B. Evaporator tubes
C. Capillary tubes
D. Throttling device
E. Refrigerant cooling tubes
Answer» B. Evaporator tubes
Discussion
20.

In case of completely dry air

A. Total heat is same as latent heat
B. Total heat is same as sensible heat
C. Total heat is sum of sensible heat and latent heat
D. Total heat is sum of sensible heat required for all individual constituents
E. None of the above
Answer» C. Total heat is sum of sensible heat and latent heat
Discussion
21.

The rate of evaporation of water will be low when

A. Rate of evaporation does not depend on relative humidity
B. Sensible heat factor
C. Relative humidity is high
D. Reactive humidity is zero
E. Relative humidity is less than 50%
Answer» D. Reactive humidity is zero
Discussion
22.

Out of the following refrigerants which one will provide highest compressor displacement per tonne of refrigeration in a vapour compression system operating between fixed temperatures

A. Freon 22
B. Carbondioxide
C. Freon 11
D. Freon 12
E. Ammonia
Answer» D. Freon 12
Discussion
23.

In case of wet bulb depression is zero, it can be concluded that

A. Rain is likely to occur
B. Storm is likely to hit the place
C. Relative humidity is zero
D. Relative humidity is 100%
E. None of the above
Answer» E. None of the above
Discussion
24.

In a psychrometric chart vertical lines indicate

A. Dew point temperature
B. Dry bulb temperature
C. Wet bulb temperature
D. Percentage humidity
E. Relative humidity
Answer» C. Wet bulb temperature
Discussion
25.

In halide torch test if there is leakage of refrigerant, the colour of flame with change to

A. Violet or orange
B. Red or pink
C. Blue or bright green
D. Black or grey
E. Yellow
Answer» D. Black or grey
Discussion
26.

If a refrigerator compressor cuts out on starter overloads the probable reason could be

A. Low line voltage
B. Suction pressure high
C. Discharge pressure high
D. Compressor tight
E. Any of the above
Answer» F.
Discussion
27.

Two thermometers are constructed in the same way except that one has a spherical bulb and the other an elongated cylindrical bulb. Which one will respond quickly to temperature change?

A. Spherical bulb thermometer
B. Cylindrical bulb thermometer
C. Both will respond in identical manner
D. Cannot be ascertained on the basis of information provided
E. None of the above
Answer» C. Both will respond in identical manner
Discussion
28.

Air and other non-condensable gases (foul gases) get into a refrigeration system through

A. Decomposition of refrigerant in contact with impurities
B. Breakdown of oil
C. Under vacuum operation or during maintenance work
D. Corrosion
E. Any of the above
Answer» F.
Discussion
29.

Which of the following refrigerant compressor is not classified as positive displacement compressor

A. Reciprocating compressor
B. Centrifugal compressor
C. Rotary compressor
D. Screw compressor
E. None of the above
Answer» C. Rotary compressor
Discussion
30.

In electrolus refrigerator

A. Hydrogen evaporates in ammonia
B. Ammonia evaporates in hydrogen
C. Hydrogen is absorbed in water
D. Ammonia is absorbed in hydrogen
E. Ammonia is absorbed in water
Answer» C. Hydrogen is absorbed in water
Discussion
31.

Dehumidification means

A. Removing humidity from a space
B. Reducing the quantity of water vapour in a space
C. Reducing the moisture content of a substance
D. Any of the above
E. None of the above
Answer» D. Any of the above
Discussion
32.

During sensible heating of air

A. Dry bulb temperature increases while enthalpy of moist air decreases
B. 10,000 m height above the surface of earth
C. Both dry bulb temperature as well as enthalpy decrease
D. Both dry bulb temperature as well as enthalpy increase
E. Dry bulb temperature decreases while enthalpy of moist air increases
Answer» E. Dry bulb temperature decreases while enthalpy of moist air increases
Discussion
33.

The effect of under cooling the refrigerant is to

A. Reducing the COP of the cycle
B. Increase the COP of the cycle
C. Reduce the refrigerating effect
D. Increase the super heat of vapour
E. None of the above
Answer» C. Reduce the refrigerating effect
Discussion
34.

Refrigerant 717 is

A. Freon 22
B. Air
C. Freon 12
D. Carbondioxide
E. Ammonia
Answer» F.
Discussion
35.

If dry bulb temperature is 25?C and wet bulb temperature is 18?C, then which of the following temperatures could possibly represent dew point?

A. 14?C
B. 25?C
C. 40?C
D. 43?C
E. 18?C
Answer» B. 25?C
Discussion
36.

The relation between vapour pressure to the enthalpy of vaporisation is expressed in

A. Vander wall's equation
B. Energy equation
C. Maxwell's equation
D. Clausius Clapeyron equation
E. Lewis equation
Answer» E. Lewis equation
Discussion
37.

A low wet bulb temperature indicates

A. Very cool air
B. Very low humidity
C. Very low atmospheric temperature
D. (A) and (B) above
E. (A) and (C) above
Answer» E. (A) and (C) above
Discussion
38.

Clear ice

A. Is pure ice
B. Contains dissolved air
C. Contains dissolved gases
D. Is produced by blowing air during freezing
E. None of the above
Answer» E. None of the above
Discussion
39.

Which of the following refrigerant has the lowest specific volume?

A. Ammonia
B. Freon 22
C. All the refrigerants have identical specific volume
D. Freon 12
E. Carbondioxide
Answer» F.
Discussion
40.

For a sensible heating the air is passed over a heating coil which may be

A. Heated by electric resistance
B. Heated by passing hot water through the coil
C. Heated by passing steam through the coil
D. Heated by direct solar radiations
E. Heated by any of the above methods
Answer» F.
Discussion
41.

Frost on cooling coils

A. Increases heat transfer
B. Reduces evaporator temperature
C. Improves COP of the system
D. Acts as an insulation, increasing power consumption
E. Reduces power consumption
Answer» E. Reduces power consumption
Discussion
42.

A plant has one 300 ton and one 500 ton centrifugal unit. The total flow of brine is 6400 litres per minute. What should be the distribution of brine flow through each unit

A. 3200 litres each
B. 2400 litres through 300 ton plant and 4000 litres through 500 ton plant
C. 4000 litres through 300 ton plant and 2400 litres through 500 ton plant
D. Same brine should flow through both
E. None of the above
Answer» D. Same brine should flow through both
Discussion
43.

One a psychrometric chart cooling and humidification process using spray can be shown by

A. A line parallel to wet bulb temperature lines
B. A curve
C. A line parallel to dry bulb temperature lines
D. A horizontal line
E. A vertical line
Answer» B. A curve
Discussion
44.

In a vapour compression cycle the refrigerant immediately after expansion valve is in

A. Liquid form
B. Wet vapour form
C. Dry vapour form
D. Dry and saturated vapour form
E. None of the above
Answer» C. Dry vapour form
Discussion
45.

On a psychrometric chart sensible heating or cooling is represented by

A. A horizontal line
B. A vertical line
C. Inclined line
D. Curved line
E. None of the above
Answer» B. A vertical line
Discussion
46.

Which of the following has lowest COP?

A. Vapour compression cycle using wet compression
B. Vapour compression cycle with superheated vapour at the end of compression
C. Vapour absorption cycle
D. Vapour compression cycle using dry compression
E. All the refrigerants have identical specific volume
Answer» D. Vapour compression cycle using dry compression
Discussion
47.

If wet bulb temperature is same as dew point, the relative humidity of air will be

A. 0
B. 25
C. 67
D. 100
E. 50
Answer» E. 50
Discussion
48.

Reversed Carnot cycle assumes that all processes in the cycle are

A. Non-flow only
B. 10,000 m height above the surface of earth
C. Transient flow
D. Non flow or steady flow
E. Steady flow only
Answer» E. Steady flow only
Discussion
49.

A refrigerating system operates on the reversed Carnot cycle. The higher temperature of the refrigerant in the system is 40?C and the lower is - 15?C. The capacity is to be 10 tons. Neglecting all losses, the coefficient of performance of the system would be

A. 2.67
B. 3.75
C. 9.41
D. 4.69
E. 7.36
Answer» E. 7.36
Discussion
50.

When the lower temperature is fixed, the COP of a refrigerating machine can be improved by

A. Operating the machine at higher speeds
B. Raising the higher temperature
C. Lowering the higher temperature
D. None of the above
Answer» E.
Discussion