MCQ-Refrigeration and Airconditioning
1-During which component of vapour
compression refrigeration system, the enthalpy remains constant:
(A) Evaporator
(B) Compressor
(C) Throttle valve
(D) None
2-Which one of the following is a CFC refrigerant?
(A) R 744
(B) R 290
(C) R 502
(D) R 718
3-In sensible cooling process the relative humidity:
(A) decreases
(B) increases
(C) remains constant
(D) none of the above
4-In psychrometric chart, dew point temperature lines are
(A) horizontal
(B) vertical
(C) curved
(D) straight lines slopping downwards to the right
5-In psychrometric chart, specific humidity lines are:
(A) vertical
(B) horizontal
(C) inclined
(D) curved lines
6-Commonly used refrigerant in commercial ice plant is
(A) CO2
(B) Freon 12
(C) Ammonia
(D) Air
7-Accumulator is provided for
(A) Storing of liquid refrigerant
(B) exchange of heat
(C) storing of unvaporized liquid
(D) condensing gas
8-Oil separator if fitted in between
(A) Condenser and evaporator
(B) On the suction line
(C) compressor and condenser
(D) at the receiver outlet
9-An air washer can work as:
(A) Humidifier
(B) Dehumidifier
(C) Filter
(D) All of the above
10-Sling psychrometer is used to measure
(A) only dry bulb temperature
(B) only wet bulb temperature
(C) dry and wet bulb temperature
(D) relative humidity
(A) 335 kJ/kg
(B) 144 BTU/lb
(C) 80 kilo-calorie/kg
(D) all of the above
12-Select the wrong characteristics of refrigerant:
(A) low latent heat
(B) low boiling point
(C) high thermal conductivity
(D) none of the above
13-Sensible heat factor is:
(A) Sensible heat/Latent heat
(B) Total heat/Sensible heat
(C) Latent heat/Sensible heat
(D) Sensible heat/Total heat
14-The function of duct in air conditioning unit is:
(A) air cooling
(B) air cleaning
(C) air drying
(D) air distribution
15-Process of changing solid into vapour state without passing
through liquid state is:
(A) super heating
(B) sublimation
(C) subcooling
(D) triple point
16-Amount of heat required to raise the temperature of one unit of
substance through 1 degree is called:
(A) C.H.U.
(B) B.T.U.
(C) Calorie
(D) Specific heat
17-The COP of a domestic air conditioning in comparison to
domestic refrigerator will be:
(A) same
(B) less
(C) more
(D) depends upon weather conditions
18-Solenoid valve is operated:
(A) electrically
(B) by hand
(C) by gas pressure
(D) by oil pressure
19-Subcooling is a process of cooling the refrigerant in vapour
compression refrigeration system before:
(A) evaporation
(B) throttling
(C) condensation
(D) compression
20-Pump down the system for:
(A) more cooling effect
(B) to check compressor efficiency
(C) gas charging
(D) to attend maintenance in low side
ANSWERS: 16-(D), 17-(C), 18-(A), 19-(B), 20-(D)
21-The process in winter air conditioning is
(A) Dehumidification
(B) Heating and humidification
(C) Humidification
(D) Cooling and dehumidification
22-A thermostatic expansion valve function with
(A) suction pressure
(B) discharge pressure
(C) discharge temperature
(D) suction temperature
23-The colour of the flame of halide torch in case of leakage of
Freon refrigerant will change t:
(A) Purple
(B) Pink
(C) Bright green
(D) Blue
24-Liquid charged in thermostatic expansion valves sensing bulb
is:
(A) alcohol
(B) same refrigerant
(C) mercury
(D) nitrogen
25-The oil used with 134A refrigerant is:
(A) Mineral oil
(B) Capilla D
(C) Polyol ester oil
(D) Lubricating oil
ANSWERS: 21-(B), 22-(A), 23-(C), 24-(B), 25-(C)
26-The difference between DBT and WBT is called:
(A) wet bulb depression
(B) dew point depression
(C) effective temperature
(D) adiabatic saturation temperature
27-A device which is used to find relative humidity:
(A) Pyrometer
(B) Anemometer
(C) Hydrometer
(D) Hygrometer
28-Which type of valve is used in a reciprocating refrigeration
compressor?
(A) rotary valve
(B) poppet valve
(C) ring plate
(D) glob valve
29-The capacity of visible cooler is expressed in:
(A) cubic feet
(B) litres
(C) k.cal/TR
(D) tons of refrigeration
30-Chemical name of Freon 22 is
(A) Dichlorodifluoro methane
(B) Monochlorodifluoro methane
(C) Trichloromonofluoro methane
(D) Dichloromonofluoro methane
ANSWERS: 26-(A), 27-(D), 28-(B), 29-(B), 30-(B)
31-The operation theatre in a hospital is to be air conditioned.
Suggest the percentage of outside air being circulated in the theatre:
(A) zero
(B) 20
(C) 50
(D) 100
32-Which of the following refrigerant has the lowest boiling
point?
(A) carbon dioxide
(B) Ammonia
(C) Hydrogen
(D) Freon 12
33-Auto defrost is operated by
(A) Evaporator fan
(B) Thermostat
(C) Timer watch
(D) Heating element
34-The absolute zero temperature corresponds on the condition when
(A) all the substances exit only as solids
(B) volume of a gas reduces to zero
(C) kinetic energy of gas molecules becomes zero
(D) no pressure is exerted by the gas
35-Sum of atmospheric pressure and gauge pressure is called
(A) Total pressure
(B) Absolute pressure
(C) Normal pressure
(D) Natural pressure
36-The effectiveness of the cooling tower is dependent on:
(A) dry bulb temperature of the air
(B) direction of the flow of air
(C) wet bulb temperature of the air
(D) none of the above
37-One micron of vaccum is equal to
(A) 0.1 MM Hg
(B) 0.01 MM Hg
(C) 0.001 MM Hg
(D) 0.0001 MM Hg
38-In a flooded evaporator which of the following types of
expansion device is employed?
(A) float valve
(B) capillary tube
(C) automatic expansion valve
(D) thermostatic expansion valve
39-In a thermal electric expansion valve which senses the suction
temperature is
(A) Transformer
(B) Thermister
(C) Thermostat
(D) Rheostat
40-The specific humidity is the mass of water vapour present in
(A) 1 kg of dry air
(B) 1 m3 of dry air
(C) 1 m3 of wet air
(D) 1 kg of wet air
ANSWERS: 36-(C), 37-(C), 38-(A), 39-(B), 40-(A)
