Refrigeration & Air-Conditioning 1000+ MCQ with answer for SBI Clerk

1. 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

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

3. A condenser of refrigeration system rejects heat at the rate of 120 kW, while its compressor consumes a power of 30 kW. The coefficient of performance of the system will be
A. 1/4
B. 1/3
C. 3
D. 4
Answer : D

4. Chaperon equation is a relation between
A. Temperature, pressure and enthalpy
B. Specific volume and enthalpy
C. Temperature and enthalpy
D. Temperature, pressure, specific volume and enthalpy
Answer : D

5. 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

6. The vertical and uniformly spaced lines on a psychrometric chart indicates
A. Dry bulb temperature
B. Wet bulb temperature
C. Dew point temperature
D. Specific humidity
Answer : A

7. The boiling point of ammonia is
A. -10.5°C
B. -30°C
C. -33.3°C
D. -77.7°C
Answer : C

8. Rating of a domestic refrigerator is of the order of
A. 0.1 ton
B. 5 tons
C. 10 tons
D. 40 tons
Answer : A

9. In S.J. unit, one ton of refrigeration is equal to
A. 210 kJ/ min
B. 21 kJ/ min
C. 420 kJ/ min
D. 840 kJ/ min
Answer : A

10. Which of the following refrigerant has the lowest boiling point?
A. Ammonia
B. Carbon dioxide
C. Sulphur dioxide
D. R-12
Answer : B

11. 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

12. The boiling point of ammonia is
A. 100°C
B. 50°C
C. 33.3°C
D. 0°C
Answer : C

13. 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

14. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice
A. In 1 hour
B. In 1 minute
C. In 24 hours
D. In 12 hours
Answer : C

15. Allowable pressure on high pressure side or ammonia absorption system is of the order of
A. Atmospheric pressure
B. Slightly above atmospheric pressure
C. 24 bars
D. 56 bars
Answer : D

16. During heating and dehumidification process, dry bulb temperature
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : B

17. The undesirable property of a refrigerant is
A. Non-toxic
B. Non-flammable
C. Non-explosive
D. High boiling point
Answer : D

18. The superheating in a refrigeration cycle
A. Does not alter C.O.P.
B. Increases C.O.P.
C. Decreases C.O.P.
D. None of these
Answer : C

19. 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

20. Short horizontal lines on pressure-enthalpy chart show
A. Constant pressure lines
B. Constant temperature lines
C. Constant total heat lines
D. Constant entropy lines
Answer : A

21. Critical temperature is the temperature above which
A. A gas will never liquefy
B. A gas will immediately liquefy
C. Water will evaporate
D. Water will never evaporate
Answer : A

22. During cooling and dehumidification, dry bulb temperature
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : C

23. The vapour compression refrigerator employs the following cycle
A. Rankine
B. Carnot
C. Reversed Rankine
D. Reversed Carnot
Answer : D

24. Bell Coleman cycle is a
A. Reversed Carnot cycle
B. Reversed Otto cycle
C. Reversed Joule cycle
D. Reversed Rankine cycle
Answer : C

25. 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

26. Most air cooled condensers are designed to operate with a temperature difference of
A. 5°C
B. 8°C
C. 14°C
D. 22°C
Answer : C

27. If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of -23°C, then the Carnot COP will be
A. 0.2
B. 1.2
C. 5
D. 6
Answer : D

28. 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

29. 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

30. A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of -23°C. The Carnot coefficient of performance of cycle will be
A. 0.2
B. 1.2
C. 5
D. 6
Answer : C

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

32. Cooling water is required for following equipment in ammonia absorption plant
A. Condenser
B. Evaporator
C. Absorber
D. Condenser, absorber and separator (rectifier)
Answer : D

33. The specific humidity during cooling and dehumidification
A. Remains constant
B. Increases
C. Decreases
D. None of these
Answer : C

34. In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in
A. Condenser
B. Evaporator
C. Absorber
D. None of these
Answer : A

35. 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

36. 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

37. The difference between dry bulb temperature and dew point temperature, is called
A. Dry bulb depression
B. Wet bulb depression
C. Dew point depression
D. Degree of saturation
Answer : C

38. The relative humidity is defined as
A. The mass of water vapour present in 1 m3 of dry air
B. The mass of water vapour present in 1 kg of dry air
C. The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.
D. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure
Answer : D

39. The central air conditioning system has ________ overall efficiency as compared to individual systems.
A. Same
B. Lower
C. Higher
D. None of these
Answer : C

40. Which of the following statement is wrong?
A. The value of C.O.P. is always greater than one.
B. In a vapour compression system, the condition of refrigerant before entering the compressor is dry saturated vapour.
C. The space between the saturated liquid line and saturated vapour line, in a pressure enthalpy chart, is wet vapour region.
D. None of the above
Answer : D

41. The sub-cooling in a refrigeration cycle
A. Does not alter C.O.P.
B. Increases C.O.P.
C. Decreases C.O.P.
D. None of these
Answer : B

42. Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere?
A. Ammonia
B. Carbon dioxide
C. Sulphur dioxide
D. Fluorine
Answer : D

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

44. In a refrigeration system, heat absorbed in comparison to heat rejected is
A. More
B. Less
C. Same
D. More for small capacity and less for high capacity
Answer : B

45. The thermostatic expansion valve operates on the changes in the
A. Degree of superheat at exit from the evaporator
B. Temperature of the evaporator
C. Pressure in the evaporator
D. None of the above
Answer : A

46. The fluids used in Electrolux refrigerator are
A. Water and hydrogen
B. Ammonia and hydrogen
C. Ammonia, water and hydrogen
D. None of these
Answer : C

47. In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor)
A. B.P.F. - 1
B. 1 - B. P.F.
C. 1/ B.P.F.
D. 1 + B.P.F.
Answer : B

48. 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

49. An infinite parallel planes with emissivities e? and e?, the interchange factor for radiation from surface 1 to surface 2 is given by
A. (e? + e?)/ e? + e? - e?e?
B. 1/e? + 1/e?
C. e? + e?
D. e?e?
Answer : A

50. The boiling point of carbon dioxide is
A. -20.5°C
B. -50°C
C. -63.3°C
D. -78.3°C
Answer : D