Refrigeration & Air-Conditioning 1000+ MCQ with answer for SSC CHSL

1. A vapour absorption refrigeration system
A. Gives noisy operation
B. Gives quiet operation
C. Requires little power consumption
D. Cools below 0°C
Answer : B

2. Highest pressure encountered in a refrigeration system should be
A. Critical pressure of refrigerant
B. Much below critical pressure
C. Much above critical pressure
D. Near critical pressure
Answer : B

3. The specific humidity during dehumidification process
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : C

4. The superheated vapour region, in a pressure enthalpy chart, is represented by the space
A. To the left of saturated liquid line
B. To the right of saturated liquid line
C. Between the saturated liquid line and saturated vapour line
D. None of the above
Answer : C

5. A refrigeration system
A. Removes heat from a low temperature body and delivers it to a high temperature body
B. Removes heat from a high temperature body and delivers it to a low temperature body
C. Rejects energy to a low temperature body
D. None of the above
Answer : A

6. The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called
A. Kinetic theory of gases
B. Newton's law of gases
C. Dalton's law of partial pressures
D. Avogadro's hypothesis
Answer : C

7. The thermostatic expansion valve is also called
A. Constant pressure valve
B. Constant temperature valve
C. Constant superheat valve
D. None of these
Answer : C

8. A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in ________ power per tonne of refrigeration.
A. Same
B. Lower
C. Higher
D. None of these
Answer : B

9. The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is
A. High pressure saturated liquid
B. Wet vapour
C. Very wet vapour
D. Dry vapour
Answer : C

10. As relative humidity decreases, the dew point temperature will be ________ wet bulb temperature.
A. Same as
B. Lower than
C. Higher than
D. None of these
Answer : B

11. The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to
A. Bright green
B. Yellow
C. Red
D. Orange
Answer : A

12. Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system
A. Strong solution to weak solution
B. Weak solution to strong solution
C. Strong solution to ammonia vapour
D. Ammonia vapours to weak solution
Answer : B

13. The sensible heat factor during the heating and humidification process is given by (where h? = Enthalpy of air entering the heating coil, h? = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)
A. (hA - h2)/ (h1 - h2)
B. (h2 - hA)/ (h1 - h2)
C. (h1 - h2)/ (hA - h2)
D. (hA - h1)/ (h2 - h1)
Answer : D

14. Most of the domestic refrigerators work on the following refrigeration system
A. Vapour compression
B. Vapour absorption
C. Carnot cycle
D. Electrolux refrigerator
Answer : A

15. The general rule for rating refrigeration systems (excepting for CO? system) is to approximate following h.p. per ton of refrigeration
A. 0.1 to 0.5 h.p. per ton of refrigeration
B. 0.5 to 0.8 h.p. per ton of refrigeration
C. 1 to 2 h.p. per ton of refrigeration
D. 2 to 5 h.p. per ton of refrigeration
Answer : C

16. At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant
A. Decreases
B. Increases
C. Remain same
D. Depends on other factors
Answer : B

17. In a refrigeration cycle, the flow of refrigerant is controlled by
A. Compressor
B. Condenser
C. Evaporator
D. Expansion valve
Answer : D

18. For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then
A. Bigger cabinet should be used
B. Smaller cabinet should be used
C. Perfectly tight vapour seal should be used
D. Refrigerant with lower evaporation temperature should be used
Answer : C

19. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.
A. More
B. Less
C. Equally
D. Unpredictable
Answer : A

20. Highest temperature encountered in refrigeration cycle should be
A. Near critical temperature of refrigerant
B. Above critical temperature
C. At critical Temperature
D. Much below critical temperature
Answer : D

21. In vapour compression cycle the condition off refrigerant is dry saturated vapour
A. After passing through the condenser
B. Before passing through the condenser
C. After passing through the expansion or throttle valve
D. Before entering the compressor
Answer : D

22. In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid
A. After passing through the condenser
B. Before passing through the condenser
C. After passing through the expansion or throttle valve
D. Before entering the expansion valve
Answer : D

23. The process, generally used in summer air conditioning to cool and dehumidify the air, is called
A. Humidification
B. Dehumidification
C. Heating and humidification
D. Cooling and dehumidification
Answer : D

24. The relative coefficient of performance is
A. Actual COP/theoretical COP
B. Theoretical COP/actual COP
C. Actual COP × theoretical COP
D. None of these
Answer : A

25. The temperature of air recorded by a thermometer, when it is not affected by the moisture present in the air, is called
A. Wet bulb temperature
B. Dry bulb temperature
C. Dew point temperature
D. None of these
Answer : B

26. The refrigerant for a refrigerator should have
A. High sensible heat
B. High total heat
C. High latent heat
D. Low latent heat
Answer : C

27. In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is
A. Heated and dehumidified
B. Heated and humidified
C. Cooled and humidified
D. Cooled and dehumidified
Answer : B

28. The domestic refrigerator uses following type of compressor
A. Centrifugal
B. Axial
C. Miniature sealed unit
D. Piston type reciprocating
Answer : D

29. In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be
A. 0.3
B. 0.6
C. 0.67
D. 1.5
Answer : B

30. The wet bulb temperature during sensible heating of air
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : B

31. The wet bulb temperature at 100% relative humidity is ________ dew point temperature.
A. Same as
B. Lower than
C. Higher than
D. None of these
Answer : A

32. The emissivity of a polished silver body is __________ as compared to black body.
A. Same
B. Low
C. Very low
D. High
Answer : C

33. A bootstrap air cooling system has
A. One heat exchanger
B. Two heat exchangers
C. Three heat exchangers
D. Four heat exchangers
Answer : B

34. In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to
A. Collect liquid refrigerant and prevent it from going to compressor
B. Detect liquid in vapour
C. Superheat the vapour
D. Collect vapours
Answer : A

35. The pressure at the outlet of a refrigerant compressor is called
A. Suction pressure
B. Discharge pressure
C. Critical pressure
D. Back pressure
Answer : B

36. Air refrigerator works on
A. Reversed Carnot cycle
B. Bell Coleman cycle
C. Both (A) and (B)
D. None of these
Answer : C

37. In a vapour compression system, the condition of refrigerant is dry saturated vapour
A. Before entering the compressor
B. After leaving the compressor
C. Before entering the condenser
D. After leaving the condenser
Answer : A

38. The temperature of ammonia after compression in a vapour compression system is
A. 20 to 50°C
B. 50 to 70°C
C. 70 to 110°C
D. None of these
Answer : C

39. One tonne of refrigeration (1TR) means that the heat removing capacity is
A. 21 kJ/min
B. 210 kJ/min
C. 420 kJ/min
D. 620 kJ/min
Answer : B

40. For unsaturated air, the dew point temperature is __________ wet bulb temperature.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B

41. In which of the following refrigeration system, waste heat can be effectively used?
A. Vapour compression cycle
B. Vapour absorption cycle
C. Air refrigeration cycle
D. None of these
Answer : B

42. The curved lines on a psychrometric chart indicates
A. Dry bulb temperature
B. Wet bulb temperature
C. Dew point temperature
D. Relative humidity
Answer : D

43. The C.O.P. of an absorption type refrigerator is given by (where T? = Temperature at which the working substance receives heat, T? = Temperature of cooling water, and T? = Evaporator temperature)
A. [T? (T? - T?)] / [T? (T? - T?)]
B. [T? (T? - T?)]/ [T? (T? - T?)]
C. [T? (T? - T?)] / [T? (T? - T?)]
D. [T? (T? - T?)] / [T? (T? - T?)]
Answer : B

44. A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is
A. Ammonia
B. Carbon dioxide
C. Freon
D. Brine
Answer : B

45. Absorption system normally uses the following refrigerant
A. Freon-11
B. Freon-22
C. CO2
D. Ammonia
Answer : D

46. The freezing point of sulphur dioxide is
A. -56.6°C
B. -75.2°C
C. -77.7°C
D. -135.8°C
Answer : B

47. The evolution of heat of solution takes place in ammonia absorption plant when
A. Ammonia vapour goes into solution
B. Ammonia vapour is driven out of solution
C. Lithium bromide mixes with ammonia
D. Weak solution mixes with strong solution
Answer : A

48. Mass flow ratio of NH? in comparison to Freon12 for same refrigeration load and same temperature limits is of the order of
A. 1 : 1
B. 1 : 9
C. 9 : 1
D. 1 : 3
Answer : B

49. Air refrigeration cycle is used in
A. Domestic refrigerators
B. Commercial refrigerators
C. Air conditioning
D. Gas liquefaction
Answer : D

50. The coefficient of performance is the ratio of the refrigerant effect to the
A. Heat of compression
B. Work done by compressor
C. Enthalpy increase in compressor
D. All of the above
Answer : D