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.

101.

A Bell-Coleman cycle is

A. Reversed Otto cycle
B. Reversed Carnot cycle
C. Reversed Sterling cycle
D. Reversed Joule cycle
E. Reversed Rankine cycle
Answer» E. Reversed Rankine cycle
Discussion
102.

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

A. 0.8
B. 1.2
C. 0.2
D. 1.25
E. 5
Answer» C. 0.2
Discussion
103.

Which of the following is not a dehydrator?

A. Silica sel
B. Molecular sieve
C. Calcium chloride
D. Sodium chloride
E. All of the above
Answer» F.
Discussion
104.

In rainy season desert coolers become ineffective

A. Because of low temperature
B. Pleasant weather
C. Rain serves the purpose of cooler
D. Humidity of air increases
E. None of the above
Answer» E. None of the above
Discussion
105.

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

A. Capacitor start type
B. Shaded pole type
C. Starting torque is same in all motors
D. Permanent split capacitor type
E. Capacitor start and capacitor run type
Answer» C. Starting torque is same in all motors
Discussion
106.

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

A. 0.1 ton of cold water
B. One tonne of cold water
C. The change is gradual throughout the cycle
D. More than one tonne of cold water
E. Half ton of cold water
Answer» E. Half ton of cold water
Discussion
107.

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

A. Wet vapour, wet vapour
B. Dry saturated, wet vapour
C. Dry saturated, dry saturated
D. Liquid, liquid
E. Dry saturated, saturated liquid
Answer» F.
Discussion
108.

In vapour absorption system using ammonia, water is required for

A. Absorber only
B. Separator only
C. Condenser, absorber and separator
D. Condenser only
E. Condenser and absorber
Answer» D. Condenser only
Discussion
109.

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

A. For defrosting evaporator coils
B. To cool compressor cylinder only
C. To cool refrigerant in evaporator
D. To cool refrigerant in condenser
E. None of the above
Answer» E. None of the above
Discussion
110.

During air conditioning whenever two or more streams of moist air are mixed they follow

A. Isothermal process
B. Polytropic process
C. Constant pressure process
D. Polytropic process
E. Adiabatic process
Answer» F.
Discussion
111.

In a refrigerating system work done per kg of air is 20 kcal and heat extracted per kg of air is 25 kcal. The quantity of refrigerant used is 10 kg. The coefficient of performance of the system would be

A. 0.8
B. 12.5
C. 5
D. 8
E. 1.25
Answer» F.
Discussion
112.

Brine is always used as a secondary refrigerant in

A. Cold storage plant
B. Milk chilling plant
C. Cinema hall air conditioning plants
D. Ice plant
E. All of the above
Answer» E. All of the above
Discussion
113.

When moisture is removed from air at constant dry bulb temperature the process is known as

A. Drying
B. Sensible cooling
C. Aeration
D. Deionisation
E. Dehumidification
Answer» F.
Discussion
114.

In a mechanical refrigeration system the refrigerant occurs as liquid (or very wet vapour) between

A. Before and after compressor
B. Expansion valve or evaporator
C. Condenser and expansion valve
D. Evaporation valve and compressor
E. Compressor outlet and condenser
Answer» D. Evaporation valve and compressor
Discussion
115.

Air for air conditioning of aircraft cabin is obtained by

A. Compressing ambient air
B. Turbine exhaust
C. Bleeding from air compressor
D. Dehumidifying cabin air
E. Recycling cabin air
Answer» D. Dehumidifying cabin air
Discussion
116.

Which of the following symptoms will indicate under charging of a vapour compressor refrigeration cycle?

A. Compressor runs continuously
B. Frost on suction line
C. Low suction pressure
D. Low head pressure
E. All of the above
Answer» C. Low suction pressure
Discussion
117.

Refrigerant R-40 is

A. Air
B. Methyl chloride
C. Glycol
D. Brine
E. None of the above
Answer» C. Glycol
Discussion
118.

A refrigerant is added to vapour compression cycle through

A. High side in vapour form
B. High side in liquid form
C. Low side in liquid form
D. None of the above
E. Any of the above
Answer» C. Low side in liquid form
Discussion
119.

At 100% humidity

A. We bulb temperature is same as atmospheric temperature
B. Dry bulb temperature is same as atmospheric temperature
C. Wet bulb temperature is same as dry bulb temperature
D. Dry bulb temperature is exactly half the wet bulb temperature
E. Wet bulb temperature is exactly half the dry bulb temperature
Answer» D. Dry bulb temperature is exactly half the wet bulb temperature
Discussion
120.

In a ammonia vapour compression cycle during gas charging the connection is made

A. Anywhere in the cycle
B. At the compressor cycle
C. On low pressure side near evaporat
D. At the compressor outlet
E. On high pressure side close to receiver
Answer» F.
Discussion
121.

A cooling tower in a refrigeration system

A. Removes heat from refrigerant
B. Removes heat from brine
C. Removes heat from lubricating oil
D. Removes heat from hot water coming out of condenser
E. None of the above
Answer» E. None of the above
Discussion
122.

Cooling towers are used for cooling water

A. To be used for cooling the compressor
B. To be used for filtration of air
C. To be injected in circulating air
D. To be used for humidification
E. To be used for cooling the building
Answer» B. To be used for filtration of air
Discussion
123.

The ratio of specific humidity of moist air to the specific immidity of the saturated air at the same temperature, is known as

A. Absolute humidity
B. Degree of saturation and degree of reaction
C. Relative humidity
D. Any of the above
E. None of the above
Answer» C. Relative humidity
Discussion
124.

In a newly charged ammonia compression system, the clicking sound in the expansion valve indicates

A. High pressure after compression
B. Leakage of ammonia
C. Excessive ammonia charged
D. Lack of ammonia
E. Evaporator coils chocked
Answer» E. Evaporator coils chocked
Discussion
125.

Defrosting in a refrigerator may be done by

A. Stopping the compressor for a while
B. Opening the door of refrigerator
C. Placing trays of warm water in the refrigerator
D. Any of the above
E. None of the above
Answer» E. None of the above
Discussion
126.

In central air conditioning system

A. Entire equipment is placed in the air conditioned space
B. There is only one machine which performs the function of air conditioning
C. All the major equipment is located in one central space removed from the air to be conditioned
D. Is used when small area is to be air conditioned
E. None of the above
Answer» D. Is used when small area is to be air conditioned
Discussion
127.

The horse power per ton of refrigerating effect when ammonia is used as a refrigerant, will be nearly

A. 5
B. 2
C. 0.1
D. 0.5
E. 1
Answer» F.
Discussion
128.

The difference between wet and dry bulb temperature

A. Increases at atmospheric temperature
B. Increases as air gets wet
C. Increases as air gets drier
D. Remains constant always
E. None of the above
Answer» D. Remains constant always
Discussion
129.

Refrigerant 744 is

A. Carbondioxide
B. Freon 22
C. Freon 12
D. Air
E. Ammonia
Answer» B. Freon 22
Discussion
130.

Dalton's law of partial pressure state that

A. All gases exert partial pressures only
B. All gases or mixture of gases exent partial pressures
C. All gases or mixture of gases in a container will exert their own pressure on the container entirely indipendent of the others
D. Total pressure exerted by a mixture of gases or vapours is equal to the pressure exerted by individual gases or vapours
E. None of the above
Answer» D. Total pressure exerted by a mixture of gases or vapours is equal to the pressure exerted by individual gases or vapours
Discussion
131.

Which of the following are synonyms?

A. Humidity ratio and specific humidity
B. Degree of saturation and degree of reaction
C. Sensible cooling and dehumidification
D. Relative humidity and specific humidity
E. Dehumidification
Answer» B. Degree of saturation and degree of reaction
Discussion
132.

The chemical formula for Freon-12 is

A. CCI2F2
B. CH3CL
C. CCIF3
D. CHCIF2
E. CCIF2CF3
Answer» E. CCIF2CF3
Discussion
133.

The drift loss in cooling towers is around

A. 40 to 50%
B. 1%
C. 10 to 20%
D. 2 to 5%
E. 30 to 35%
Answer» D. 2 to 5%
Discussion
134.

The coefficient of performance of a domestic refrigerator as compared to that of an air conditioner is gererally

A. Less
B. Cannot be compared
C. More
D. Air conditioner performance depends on whether conditions
E. Same
Answer» B. Cannot be compared
Discussion
135.

A hermetic compressor is

A. A reciprocating compressor
B. A valveless compressor
C. A thermodynamically efficient comprossor
D. A factory sealed unit containing motor and compressor
E. None of the above
Answer» E. None of the above
Discussion
136.

A refrigerant cycle is usually a

A. Open cycle
B. Closed cycle
C. Mixed cycle
D. Hybrid cycle
E. None of the above
Answer» C. Mixed cycle
Discussion
137.

For better performance a desert cooler

A. Should be placed inside the room
B. Should be placed outside
C. Should be mounted on window
D. Should be placed at the roof level
E. None of the above
Answer» D. Should be placed at the roof level
Discussion
138.

The statement: If a maximum of gases or vapours is enclosed in a container, each will exert its own pressure on the container entirely independent of the others and the total absolute pressure will be equal to the sum of the partial pressure exerted by each of the gases. This statement is known as

A. Newton's law of gases
B. Kinetic theory of gases
C. Avogadro's hypothesis
D. Fick's law
E. Dalton's law of partial pressures.
Answer» F.
Discussion
139.

The change in temperature resulting from a gas expanding from one constant pressure, with no heat transfer and no external work other than to maintain the constant pressure is known as

A. Dalton's law of partial pressures
B. Kinetic theory of gases
C. Avogadro's hypothesis
D. Joule - Thomoson effect
E. Law of conservation of energy
Answer» E. Law of conservation of energy
Discussion
140.

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

A. Half the water already air
B. Very high
C. Zero
D. Slow
E. Half the water already air
Answer» D. Slow
Discussion
141.

If the discharge pressure of a refrigeration compressor is too high it shows

A. Too little or to warm condenser water
B. Lack of refrigerant
C. Excessive cooling load
D. Lack of compressor lubrication
E. Any of the above
Answer» C. Excessive cooling load
Discussion
142.

Ten grams of moisture per kg of dry air is removed from atmospheric air during air conditioning and the temperature becomes 30?C. If the atmospheric conditions are 40?C DBT and 60% Relative humidity, the RH of air after refrigeration would be

A. 50%
B. 69%
C. 40%
D. 104%
E. 60%
Answer» C. 40%
Discussion
143.

The critical temperature for Freon 12 is

A. Above 100?C
B. Less than - 50?C
C. Around - 20?C
D. 0?C
E. Around 50?C
Answer» B. Less than - 50?C
Discussion
144.

Major modification required to produce temperature of - 200?C in a vapour compression refrigeration system using Freon 12 as refrigerant, is

A. Condenser capacity must be increased to handle the refrigerant
B. Size of compressor required would be large to handle volumes of vapour
C. Compression ratio has to be restricted till stronger body of compressor is needed
D. Freon 12 cannot be used for such low temperatures
E. Insulation should be capable of withstanding such low temperatures
Answer» E. Insulation should be capable of withstanding such low temperatures
Discussion
145.

The colour of the flame of halide torch in case of leakage of freon refrigerant, will change to

A. Yellow
B. Violet
C. Green
D. Orange
E. Red
Answer» D. Orange
Discussion
146.

Freon 12 is a compound consisting of stoms of

A. Carbon, hydrogen and fluorine
B. Carbon and hydrogen
C. Carbon, hydrogen, fluorine and chlorine
D. Carbon, fluorine and chlorine
E. Carbon, hydrogen and oxygen
Answer» E. Carbon, hydrogen and oxygen
Discussion
147.

The condition of refrigerant before and after compression in vapour compression cycle is

A. Wet vapour, wet vapour
B. Dry saturated vapour, liquid
C. Dry saturated vapour, superheated vapour
D. Wet vapour, cry saturated vapour
E. Liquid, wet vapour
Answer» E. Liquid, wet vapour
Discussion
148.

In which section of a vapour compression system, the refrigerant is generally in the form of a wet vapour?

A. Condenser outlet
B. Expansion valve
C. Evaporator
D. Compressor
E. Condenser inlet
Answer» D. Compressor
Discussion
149.

Freon type (halocarbons) refrigerants are

A. Poisonous
B. Coloured
C. Have peculiar odour
D. Irritating
E. Non-poisonous
Answer» F.
Discussion
150.

The leakage in a refrigeration system using freon is detected by

A. Acetylene torch
B. Halide torch
C. Sulphur stricks
D. Soap and water
E. Any of the above
Answer» C. Sulphur stricks
Discussion