RRB ALP CBT 2 RAC Question Paper MCQ (Railway Assistant Loco Pilot)

RRB ALP CBT 2 RAC Question Paper MCQ PDF Free Download. Railway Assistant Loco Pilot Mechanic Refrigeration and Air Conditioning Important Questions.

2. RRB ALP CBT 2 RAC Question Paper MCQ
Contents
RRB ALP CBT 2 RAC (Refrigeration and Air Conditioning) Mechanic 23/1/2019 Shift – 1 ................................................ 2
RRB ALP CBT 2 RAC 23/01/2019 Shift – 2 ....................................................................................................................... 11

RRB ALP CBT 2 RAC (Refrigeration and Air Conditioning) Mechanic 23/1/2019
Shift – 1
1. Capilary tube is the expansion valve used in refirgeration and air conditioning units _____
a) With more than 10 ton cooling capacity
b) With less than 3 ton cooling capacity
c) With more than 3 ton cooling capacity
d) With less than 10 ton cooling capacity
Ans. B

2. After AC installation, how should one check the performance?
a) Run unit for a minimum of 05-10 minutes
b) Run units of a minimum of 10-15 minutes
c) Run unit for a minimum of 0-05 minutes
d) Run unit for a minimum of 20-25 minutes
Ans. D

3. Convert 2-Ton refrigeration to horsepower (metric).
a) 9.56 b) 7.46 c) 8.97 d) 6.47
Ans. A

4. Improper flaring is directly related with _____
a) Leakaeg of refrigerant
b) Saving money
c) Appearance
d) Longevity of equipment
Ans. A

5. In a multi split AC system_____
a) You can set different temperatures for different rooms
b) Temperature controls are installed in each room
c) You cannot set different temperatures for different rooms
d) You cannot control temperature by single temperature controller
Ans. A

3. 6. What is the purpose of Taper reamer?
a) To finish parallel hole
b) To finish taper hole
c) To finish irregular hole
d) To finish square hole
Ans. B

7. Which type of file is suitable to file right angle finish corner?
a) Round file
b) Square file
c) Safe edge file
d) Triangular file
Ans. C

8. How the OLP is connected with refrigeration circuit of a refrigerator?
a) Parallel with Running & Starting
b) Series with Common winding
c) Series with Running winding
d) Series with Starting winding
Ans. B

9. Which rays are produced during welding?
a) X-rays
b) Gammar rays
c) Ultraviolet rays
d) Microwaves rays
Ans. C

10. A spring bender is used for –
a) bending the copper tube
b) swaging the copper tube
c) flaring the copper tube
d) straightening the copper tube
Ans. A

11. Which type of relay is used with window type air conditioner?
a) Potential relay b) PTCR
c) PTC d) electromagnetic relay
Ans. D

12. Which is not the type of air conditioner compressor?
a) Scroll b) Rotary
c) Centrifugal d) Absorption
Ans. D

4. 13. Which is not the cause of weak airflow in CAR AC?
a) Mold or mildew may have accumulaetd in the evaporator core from residual moisure.
b) Low air velocity outside car
c) Ventilation fan is not blowing air
d) The blower hose that supplies air to the blower unit has come loose
Ans. B

14.What is the use of Tap?
a) Cleanin external thread
b) Forming external thread
c) Forming internal thread
d) forming thread on nipple
Ans. C

15. The domestic refrigerator uses following type of comprssor.
a) Piston type reciprocating
b) Axial
c) Centrifugal
d) Miniature sealed unit
Ans. A

16. What will be the value of 18SWG in millimeters?
a) 1.34 mm
b) 1.14 mm
c) 1.44 mm
d) 1.24 mm
Ans. D

17. What is the colour of Argon Cylinder?
a) Maroon b) Yellow shoulder
c) Dark green shoulder d) Grey shoulder
Ans. C

18. What is the outcome of having a straight copper pipe fitting in refrigeration cycle?
a) Pressure will increase b) Pressure will not drop
c) Pressure keeps fluctuating d) Prssure will decrease
Ans. B

19. What is the use of Thermo-Volume Switch?
a) Eangaging/disengaging magnetic clutch
b) Controlling fan speed
c) Setting cooling range for thermostat
d) Controlling air flow
Ans. C

5. 20. Which is NOT a common Car air conditioning system problem?
a) Moisture deposition
b) Soiled or clogged condenser
c) Pungent odors
d) Engine backfiring
Ans. D

21. What will be the temperature of single door refrigerator’s freezer box?
a) -10
0
C
b) -18
0
C
c) -12
0
C
d) -11
0
C
Ans. B

22. Which type of snip is suitable to cut curved surfaces?
a) Bent snip
b) Scissor type snip
c) Aviation snip
d) Straight snip
Ans. A

23. Freon group of refrigerant are _____
a) Nontoxic and non-inflammable
b) Toxic and non-inflammable
c) Toxic and inflammable
d) Nontoxic and inlammable
Ans. C

24. In window type air conditioner, themostat is fixed between ___.
a) Selector switch and OLP
b) Relay and OLP
c) Running winding and condenser fan
d) Relay and winding
Ans. A

25. Where is a Cassette A/C indoor unit installed?
a) Near a window of the room b) Floor of the room
c) Wall of the room d) Roof of the room
Ans. D

26. Which refrigerant is newly introduced to replace R-22?
a) R-510D b) R-507C
c) R-410A d) R-410C
Ans. C

6. 27. What is the relation between voltage and ampere?
a) V= I + R
b) V = I
c) V = IR
d) V = I/R
Ans. C

28. Gas welding is also known as:
a) Fuel welding
b) Oxy fuel gas welding
c) Arc welding
d) Metallic welding
Ans. B

29. In an air conditionng system, the vacuum pump is required to create a vacuum state of _____.
a) 1200 microns
b) 500 microns
c) 4500 microns
d) 1500 microns
Ans. B

30. How is the condensed water drained from a cassete unit?
a) Siphon method
b) Condensation method
c) Graitational method
d) Pumping method
Ans. D

31. A cooling tower reduce water temperature close to:
a) Saturation temperature
b) Wet bulb temperature
c) Dew point temperature
d) Dry bulb temperature
Ans. B

32. The moisture in refrigerant is removed by ___
a) Evaportor b) Dehumidifier
c) Expansion valve d) Drier
Ans. D

33. Aqua ammonia is used as refrigerant in following typeof refrigeration system.
a) Absorption b) Indirect
c) Direct d) Compression
Ans. A

7. 34. What type of condenser is used in chest type deep freezer?
a) Forced, air cooled
b) Water cooled
c) Natural convention type
d) Air and water cooled
Ans. A

35. An expansion valve is fitted in the refrigeration unit.
a) After the evaporator
b) Before the condenser
c) Before the evaporator
d) Before the compressor
Ans. C

36. Condenser in a refrigeration system decrease
a) Volume only
b) Pressure only
c) Temperature and pressure
d) Temperature only
Ans. C

37. In a split AC _____
a) Compresor and condenser are part of an external unit while the evaporative coil is the indor air handling
unit
b) Compressor and condenser are part ofan internal unit while the evaporative coil is part of the outdoor
air handling unit
c) A single unit contains compresor, motors, connecting pipes and heat exchangers
d) Compresor in the AC installed on the unit itself
Ans. A

38. Which of the following refrigerant is replaced in retrofitting?
a) CFC-11
b) R-401A
c) HFC-134a
d) HCFC-2
Ans. A

39. Most of the chances of leakge in a split air conditioner are from ___
a) Compressor outer case joint
b) Swage joint
c) Processing tube joint
d) Flare joint
Ans. B

8. 40. Which s the best way of checking leak of split A/C condenser installed unit?
a) With electronic leak detctor
b) Diping in water tub
c) Hearing hissing sound
d) Smelling
Ans. A

41. Domestic refrigerator working on vapor compression cycle uses following type of expansion device.
a) Expansion valve
b) Thermostatic valve
c) Capillary tube
d) Electrically operated throttling valve
Ans. C

42. What type of relay fits with DOL starter?
a) Mechanical relay
b) Electronic relay
c) Magnetic relay
d) Electromagnetic relay
Ans. A

43. The location of the expansion device in a refrigeration cycle is between the ______ and _____
a) Receiver ; Evaporator
b) Condenser ; Receiver
c) Evaporator ; Compressor
d) Compressor ; Condenser
Ans. A

44. Which procedure of charging is recommended for better performance of an air conditioning system?
a) Feeling method
b) Pressure method
c) Charge still method
d) Weighting method
Ans. D

45. Thermal resistance of an ideal conductor would be ______
a) One b) Hundred c) Zero d) Ten
Ans. C

46. Due to the absorption of heat by evaporator, the refrigerant converts into ______
a) Saturated vapour b) liquid
c) sub cooled liquid d) saturated liquid
Ans. A

9. 47. Which is not the type of leak test for an air conditioner?
a) Dye testing for refrigerant leak
b) Nitrogen leak detector test and bubble test
c) Magnetic leak detector test
d) Electronic leak detector test
Ans. C

48. Which type of compressor is used for domestic air conditioner?
a) Hermeticlly sealed
b) Belt drive compressor
c) Semi sealed
d) Open type
Ans. A

49. What is the value of one calorie?
Ans. 4.2 Joule

50. What is the use of Heat limiter in water dispenser?
a) To maintain cold water temperature
b) To maintain normal temperature
c) To mix hot and cold water in the vessel
d) To disconnect electric power from heater in case of overheating
Ans. D

51. Forced air-cooled condenser fins are made up of ______.
a) Steel
b) Zinc
c) Brass
d) Aluminum
Ans. D

52. In a Hermetic sealed compressor ____
a) Both compressor and motor are outside of a single outer welded stel shell
b) Only compressor is confined in a single outer welded steel shell
c) Both compressor and motor are confined in a single outer welded steel shell
d) Only motor is confined in a single outer welded steel shell
Ans. C

53. The inner core of the flame in gas welding has _____ temperature
a) lowest
b) medium
c) 100
0
C
d) highest
Ans. D

10. 54. If the diameter of an wire increase then its resistance _____.
a) fuctuates
b) increases
c) decreases
d) remains the same
Ans. C

55. Which is the type of condenser used for < 3 Tons cooling capacity of a refrigeration unit?
a) Water and air cooled
b) Water cooled
c) oil cooled
d) Air cooled
Ans. D

56. Which is not the function of receiver drier in an A/C?
a) To trap contaimants that may be isnide the A/C system
b) To receive the air and dry the Ice
c) To absorb moisture that may have gotten inside the A/C system
d) To act as a temporary storage containers for oil and refrigerant when neither are needed for system
operation.
Ans. B

57. Where does higer temperature occur in a vapour compression cycle?
a) Receiver
b) Evaporator
c) Expansion valve
d) Compessor discharge
Ans. D

58. What should not be done in an air conditioning performance test?
a) Place a thermometer in the inside air inlet door
b) Open the doors
c) Turn blower to high speed
d) Set the controls for maximum cooling
Ans. A

11. RRB ALP CBT 2 RAC 23/01/2019 Shift – 2
1. ______
0
Celsius = 167 Fahrehheit
a) 348
b) 75
c) 198
d) 103
Ans. B

2. Which one of the following is related with the swage of a copper tube?
a) Gap between copper tube
b) Stud and flaring unit
c) Flux
d) Filler rod
Ans. A

3. What is the reason for condensed water of cassette air conditioner getting accumulated in the
evaporator?
a) Pump not working
b) Slope not proper
c) Humidity more than normal
d) Drain hole block
Ans. B

4. The capacity of visible cooler is expressed in
a) k.cal/TR
b) tons of refrigeration
c) litres
d) cubic feet
Ans. C

5. Which is the secondary refrigerant in an ice plant
a) Air
b) Mercury
c) Freon-22
d) Brine solution
Ans. D

6. Specific heat capacity of a substance =
a) Mass of the substance x heat capacity
b) Mas of the substance + heat capacity
c) Mass of the substance – heat capacity
d) Heat capcity / mass of the substance
Ans. D

12. 7. If the freezer box temperature is – 23
0
C, what will be the temperature in Fahrenheit?
a) -7.4
0
F
b) -9.4
0
F
c) -12.4
0
F
d) -16.4
0
F
Ans. B

8. Which of the following will happen if suction pressure is reduced in refrigeration cycle?
a) Evaporation temperature will decrease
b) Compressor capacity is increased as vapour is lighter
c) Power consumption is reduced per ton of refrigeration
d) Evaporation Temperature will increase
Ans. A

9. Reversed cornot cycle is used in ______ refrigerator
a) Electrolux
b) Vapour compressed
c) Lithium Bromide
d) Vapour absorption
Ans. B

10. Magnetic relay coil is connected in series with compressor’s ______
a) Body
b) running winding
c) starting winding
d) common winding
Ans. C

11. Which protective device disconnects the compressor sensing presure?
a) Selector switch
b) Pressure switch
c) Thermo volme
d) Thermo amplifier
Ans. C

12. Which of the following is commonly used refrigerant in commercial ice plant?
a) Ammonia b) Freon 12 c) Air d) CO2
Ans. A

13. The main process characterising a desert coler is :
a) Adiabatic Saturation b) Cooling and Dehumidification
c) Smart Cooling d) Dehumidification
Ans. A

13. 14. When retrofitting an R-12 car air conditioner with an R-134, the charge amount will be _____ of R-12
a) 50%
b) 90%
c) 60%
d) 70%
Ans. C

15. Humidification is the process of addition of moisture in air at
a) constant wet bulb temperature
b) constant latent heat
c) constant dry bulb temperature
d) constant dew point temprature
Ans. C

16. What do you mean by ‘condensing temperature’ in the context of refrigeration?
a) Temperature of freezing zone
b) Temperature of cooling medium
c) Temperature at which refrigerant gas becomes liquid
d) Temperature of evaporator
Ans. C

17. Which pulley of a car A/C compressor always rotates with engine, either when the air conditioner is on
or off?
a) Rotary pulley
b) Driver pulley
c) Jockey pulley
d) Idler pulley
Ans. C

18. Which tool is used to remove a high spot from a plain metal surface?
a) Chisel b) Hacksaw c) File d) Scrapper
Ans. D

19. Oil separator is fitted between.
a) On the suction line b) at the receiver outlet
c) compressor and condenser d) Condenser and evaporator
Ans. C

20. Which of the following is an important factor of the occupancies in an air-conditioned environment?
a) Refrigerant charging
b) Cleaning of the indoor A/C unit
c) Cleaning of the outdoor A/C unit
d) Proper air movement
Ans. C

14. 21. Sub cooling is process of cooling the refrigerant in vapor compression system _____.
a) After compression
b) Before refrigerant control
c) After refrigerant control
d) Before compression
Ans. B

22. At the time retrofitting an R-12 refrigerator with HC blend, how much refrigerant will be charged?
a) 40% of R-12
b) 70% of R-12
c) 60% of R-12
d) 90% of R-12
Ans. A

23. In the context of refrigeration, which instrument is used for checking the vacuum, charging status and
pressure, among other things?
a) Low pressure gauge
b) High pressure gauge
c) Gauge manifold fitted with gauges
d) Compound gauge
Ans. D

24. In frost-free refrigerators, frosting is done by _____.
a) De-emerging unit
b) Fuse
c) Bi-metal
d) Heater
Ans. D

25. If HFC and lubricant are intimately mixed with moisture cycle ____
a) The property of the lubricant will change
b) ice crystals will form
c) pressure will become low
d) sledge will be formed
Ans. B

26. What combination and proportion of gases will be used to set a neutral flame in gas welding?
a) Less oxygen than acetylene b) No acetylene, only oxygen
c) More oxygen than acetylene d) Oxygen and acetylene in equal proportion
Ans. D

27. The cleaning process of a refrigeration cycle involves cleaning of ______
a) refrigerant b) deposited solid and soil c) non-condensable gases d) sump oil
Ans. B

15. 28. Auto defrost is operated by _____
a) Thermostat
b) Heating element
c) Evaporator fan
d) Timer switch
Ans. C

29. Before retrofit, a refrigerator with HC is carefully assessed to check whether it ____
a) needs to meet better performance or not
b) is safe for HC blend conversion or not
c) is safe for HFC conversion or not
d) is safe for lubricant or not
Ans. B

30. In window type air conditioner when temperature is enriched in the room, which of the following
components disconnects the compressor from the power source?
a) Thermostat
b) OLP
c) Relay
d) Selector switch
Ans. B

31. How do you remove non-condensable gas and moisture from an air conditioning system?
a) By evacuation using system compressor
b) By deep evacuation using two-stage rotary vent pump
c) By evacuation using the old compressor
d) By evacuation using single-stage vacuum pump
Ans. C

32. Which gauge is used for checking the pressure in an Air Conditioning system?
a) Bourdon type pressure gauge
b) Lactometer
c) Manometer
d) Bourdon type compound gauge
Ans. D

33. In frost-free refrigerators, when does cooling not spread inside the cabinet?
a) When the thermostat is not working b) When the evaporator fan is not working
c) When the heater is not working d) When the bi-metal is not working
Ans. B

34. What is the state of refrigerant after it comes out of dry type evaporator?
a) Wet state b) super cooled c) saturated state d) super-heated
Ans. D

16. 35. The evaporative tube of water cooler is fitted _____.
a) inside the storage tank
b) away from the storage tank
c) below the condenser
d) outside the storage tank
Ans. D

36. The process of heat rejection by the refrigerant is achieved during which of the following refrigeration
cycles?
a) Condenser
b) Evaporator
c) Compressor
d) Expansion
Ans. A

37. What is the reason for formation of solid ice on the evaporator of a frost free refrigerator?
a) Auto defrosting system failure
b) Less refrigerant
c) Leakage in door gasket
d) Nonfunctioning relay
Ans. A

38. What is the name of the hand tool that has small sharp teeth in rows and is used for sharpening or
shaping material?
a) Hacksaw
b) Tap
c) Chisel
d) File
Ans. D

39. How should the gap between the compressor housing and shaft seal refrigerant escaping route be
sealed?
a) With M-seal
b) With a thin layer of compressor self-lubricating oil
c) With metal seal
d) With a cold adhesive
Ans. A

40. Which condenser needs De-scaling?
a) Water cooled condenser
b) Air cooled condenser
c) Plate type condenser
d) Forced air condenser
Ans. A

17. 41. If the end of a copper tube is NOT straightened, then _____
a) refrigerant temperature may go down
b) pressure will be increased
c) length will be short
d) swaging and flaring will be defective
Ans. D

42. In which of the following processes heat transfer does not take place?
a) Insulation
b) Conduction
c) Convection
d) Radiation
Ans. A

43. When refrigerant passes through the evaporating zone, heat is _____
a) absorbed
b) rejected
c) added
d) neither absorbed nor added
Ans. C

44. Pyrometer is an instrument used to measure _____
a) Relative humidity
b) High temperature
c) Density
d) High pressure
Ans. B

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Question Paper Links
RRB ALP CBT 2 RAC (MRAC) 23/1/2019 Shift – 1
RRB ALP CBT 2 RAC 23/1/2019 Shift - 2