Refrigeration & Air-Conditioning MCQ Solved Paper for IBPS Clerk

1. 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

2. Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since
A. These react with water vapour and cause acid rain
B. These react with plants and cause greenhouse effect
C. These react with oxygen and cause its depletion
D. These react with ozone layer
Answer : D

3. Rick up the incorrect statement
A. Lithium bromide used in vapour absorption cycle is non volatile
B. Lithium bromide plant can't operate below 0°C
C. A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing
D. Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator
Answer : C

4. 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

5. Presence of moisture in a refrigerant affects the working of
A. Compressor
B. Condenser
C. Evaporator
D. Expansion valve
Answer : D

6. In vapour compression refrigeration system, refrigerant occurs as liquid between
A. Condenser and expansion valve
B. Compressor and evaporator
C. Expansion valve and evaporator
D. Compressor and condenser
Answer : C

7. The leaks in a refrigeration system using Freon are detected by
A. Halide torch which on detection produces greenish flame lighting
B. Sulphur sticks which on detection gives white smoke
C. Using reagents
D. Smelling
Answer : A

8. 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

9. 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

10. The minimum temperature to which water can be cooled in a cooling tower is
A. Dew point temperature of air
B. Wet bulb temperature of air
C. Dry bulb temperature of air
D. Ambient air temperature
Answer : B

11. The bank of tubes at the back of domestic refrigerator is
A. Condenser tubes
B. Evaporator tubes
C. Refrigerant cooling tubes
D. Capillary tubes
Answer : A

12. The wet bulb depression is zero when relative humidity is
A. Zero
B. 0.5
C. 0.75
D. 1.0
Answer : D

13. Accumulators should have adequate volume to store refrigerant charge at least
A. 10 %
B. 25 %
C. 50 %
D. 75 %
Answer : C

14. Refrigeration in aeroplanes usually employs the following refrigerant
A. CO2
B. Freon-11
C. Freon-22
D. Air
Answer : D

15. When the lower temperature of a refrigerating machine is fixed, then the coefficient of performance can be improved by
A. Operating the machine at higher speeds
B. Operating the machine at lower speeds
C. Raising the higher temperature
D. Lowering the higher temperature
Answer : D

16. The value of C.O.P in vapour compression cycle is usually
A. Always less than unity
B. Always more than unity
C. Equal to unity
D. Any one of the above
Answer : B

17. The air cooling system mostly used in transport type aircrafts is
A. Simple air cooling system
B. Simple evaporative air cooling system
C. Bootstrap air cooling system
D. All of these
Answer : C

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

19. 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

20. A standard ice point temperature corresponds to the temperature of
A. Water at 0°C
B. Ice at 4°C
C. Solid and dry ice
D. Mixture of ice and water under equilibrium conditions
Answer : D

21. The wet bulb depression indicates _________ humidity of the air.
A. Absolute
B. Relative
C. Specific
D. None of these
Answer : B

22. 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

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

24. 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

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 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

27. Air conditioning means
A. Cooling
B. Heating
C. Dehumidifying
D. All of these
Answer : D

28. When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be
A. Positive
B. Negative
C. Zero
D. None of these
Answer : B

29. 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

30. In a bootstrap air evaporative cooling system, the evaporator is provided
A. Between the combustion chamber and the first heat exchanger
B. Between the first heat exchanger and the secondary compressor
C. Between the secondary compressor and the second heat exchanger
D. Between the second heat exchanger and the cooling turbine
Answer : D

31. A refrigerant compressor is used to
A. Raise the pressure of the refrigerant
B. Raise the temperature of the refrigerant
C. Circulate the refrigerant through the refrigerating system
D. All of the above
Answer : D

32. In vapour compression cycle using NH? as refrigerant, initial charge is filled at
A. Suction of compressor
B. Delivery of compressor
C. High pressure side close to receiver
D. Low pressure side near receiver
Answer : C

33. 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

34. Which of the following refrigerant is highly toxic and flammable?
A. Ammonia
B. Carbon dioxide
C. Sulphur dioxide
D. R-12
Answer : A

35. During sensible cooling,
A. Relative humidity remains constant
B. Wet bulb temperature increases
C. Specific humidity increases
D. Partial pressure of vapour remains constant
Answer : D

36. 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

37. The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents
A. Condensation of the refrigerant vapour
B. Evaporation of the refrigerant liquid
C. Compression of the refrigerant vapour
D. Metering of the refrigerant liquid
Answer : B

38. 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

39. In chemical dehumidification process,
A. Dew point temperature decreases
B. Wet bulb temperature decreases
C. Dry bulb temperature increases
D. All of these
Answer : D

40. 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

41. A human body feels comfortable when the heat produced by the metabolism of human body is equal to the
A. Heat dissipated to the surroundings
B. Heat stored in the human body
C. Sum of (A) and (B)
D. Difference of (A) and (B)
Answer : C

42. 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

43. In Electrolux refrigerator
A. Ammonia is absorbed in hydrogen
B. Ammonia is absorbed in water
C. Ammonia evaporates in hydrogen
D. Hydrogen evaporates in ammonia
Answer : C

44. The lowest temperature during the cycle in a vapour compression system occurs after
A. Compression
B. Expansion
C. Condensation
D. Evaporation
Answer : D

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

46. 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

47. 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

48. The humidification process, on the psychrometric chart is shown by
A. Horizontal line
B. Vertical line
C. Inclined line
D. Curved line
Answer : B

49. A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be
A. Lack of cooling water
B. Water temperature being high
C. Dirty condenser surface
D. All of these
Answer : D

50. Ammonia absorption refrigeration cycle requires
A. Very little work input
B. Maximum work input
C. Nearly same work input as for vapour compression cycle
D. Zero work input
Answer : A