McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
Chapters
| 1. |
In which part of the vapour compression cycle there is abrupt change in pressure and temperature |
| A. | Drier |
| B. | Solenoid valve |
| C. | Expansion valve |
| D. | The change is gradual throughout the cycle |
| E. | Evaporator |
| Answer» C. Expansion valve | |
| 2. |
The ratio of sensible heat to total heat is known as |
| A. | Relative humidity |
| B. | Humidification ratio |
| C. | Sensible heat factor |
| D. | Specific humidity |
| E. | Dew point |
| Answer» C. Sensible heat factor | |
| 3. |
The flow of the refrigerant in a refrigeration cycle is controlled by |
| A. | Copper tubing |
| B. | Compressor |
| C. | Expansion valve |
| D. | Evaporator |
| E. | Condenser |
| Answer» C. Expansion valve | |
| 4. |
The refrigerant used for the air-conditioning of passenger aircraft cabin is |
| A. | Air |
| B. | Carbondioxide |
| C. | Freon 11 |
| D. | Ammonia |
| E. | Freon 12 |
| Answer» B. Carbondioxide | |
| 5. |
Under increased atmospheric pressure (as compared to the standard conditions) the steam will condense at |
| A. | 100?C |
| B. | More than 100?C |
| C. | Depends on other conditions |
| D. | Less than 100?C |
| E. | Has nothing to do with pressure |
| Answer» B. More than 100?C | |
| 6. |
Which refrigerant has the highest critical point temperature? |
| A. | Ammonia |
| B. | Freon 11 |
| C. | Freon 12 |
| D. | Freon 22 |
| E. | None of the above |
| Answer» B. Freon 11 | |
| 7. |
The ratio of high temperature to low temperature for reversed Carnot refrigerator is 1.25. The COP will be |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| E. | All of the above |
| Answer» C. 4 | |
| 8. |
When the higher temperature is fixed, the COP of a refrigerating machine 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 |
| E. | None of the above |
| Answer» C. Raising the higher temperature | |
| 9. |
A reversed Carnot cycle has a COP of 4. The ratio of higher temperature to lower temperature will be |
| A. | 1.5 |
| B. | 2 |
| C. | 1.25 |
| D. | 2.5 |
| E. | None of the above |
| Answer» C. 1.25 | |
| 10. |
A plate of vane used to direct or control movement of fluid or air within the confined area is known as |
| A. | Baffle |
| B. | Bellows |
| C. | Regulator |
| D. | Diffuser |
| E. | None of the above |
| Answer» A. Baffle | |
| 11. |
The leaks of refrigerant from a cycle may be detected by |
| A. | Halide torch test |
| B. | Sulphur candle test |
| C. | Soap and water test |
| D. | Any of above |
| E. | None of the above |
| Answer» D. Any of above | |
| 12. |
Super-conductors |
| A. | Cannot be magnetised at low temperatures |
| B. | Can be rubbed with other superconductors without frictional effects at low temperatures |
| C. | Offer no resistance to flow of electricity at low remperatures |
| D. | Offer no resistance to flow of heat at low temperatures |
| E. | Offer no resistance to flow of fluids at low temperatures |
| Answer» C. Offer no resistance to flow of electricity at low remperatures | |
| 13. |
A desicant is |
| A. | A process of removing heat under controlled conditions |
| B. | A substance which reduces the viscosity of liquids |
| C. | A solid substance capable of removing moisture from a gas, liquid or solid |
| D. | Anammonia and a water solution |
| E. | Heat given off by cargo |
| Answer» C. A solid substance capable of removing moisture from a gas, liquid or solid | |
| 14. |
A device designed to remove moisture from a refrigerant is called |
| A. | Dehumidifier |
| B. | Drier |
| C. | Solenoid |
| D. | Expansion valve |
| E. | Humidstat |
| Answer» B. Drier | |
| 15. |
The difference between wet and dry bulb temperatures |
| A. | Increases at atmospheric temperature |
| B. | Increases as air gets wet |
| C. | Increases as air gets drier |
| D. | remains constant always |
| E. | None of the above |
| Answer» C. Increases as air gets drier | |
| 16. |
In a vapour compression cycle the vapour as it leaves the compressor is |
| A. | In liquid form |
| B. | Wet vapour |
| C. | Dry vapour |
| D. | Dry and saturated vapour |
| E. | None of the above |
| Answer» D. Dry and saturated vapour | |
| 17. |
Refrigerant No. 717 is |
| A. | Ammonia |
| B. | Freon 12 |
| C. | Carbondioxide |
| D. | Freon 22 |
| E. | Methyl chloride |
| Answer» A. Ammonia | |
| 18. |
In a domestic refrigerator if the compressor runs continuously, it shows that |
| A. | The system is working perfectly all right |
| B. | The refrigeration is to full capacity |
| C. | The system is overloaded |
| D. | Any of the above |
| E. | None of the above |
| Answer» C. The system is overloaded | |
| 19. |
The ability of an evaporator to absorb heat does not depends on |
| A. | Temperature difference between the evaporator and the surrounding air |
| B. | Its size, surface condition and material |
| C. | Kind of refrigerant used |
| D. | Velocity of turbulence |
| E. | Compressor speed |
| Answer» C. Kind of refrigerant used | |
| 20. |
pH value of a brine solution is |
| A. | More than |
| B. | 14 |
| C. | 70 |
| D. | Less than 7 |
| E. | Could be any value |
| Answer» E. Could be any value | |
| 21. |
In case of freon as refrigerant the pipe lines should be of |
| A. | Copper |
| B. | Brass |
| C. | Seamless steel tubes |
| D. | Stainless steel tubes |
| E. | None of the above |
| Answer» C. Seamless steel tubes | |
| 22. |
When Freon 12 is used as a refrigerant in vapour compression cycle, the mass circulated per ton of refrigerating effect will be nearly |
| A. | 1.8 kg |
| B. | 0.5 kg |
| C. | 12 kg |
| D. | 1 kg |
| E. | 0.2 kg |
| Answer» A. 1.8 kg | |
| 23. |
In control cooling water system, chromates, phosphates and silicates are added to water |
| A. | To remove odour |
| B. | To increase remove foreign particle |
| C. | To inhibit corrosion |
| D. | To prevent scale formation |
| E. | To prevent algae growth |
| Answer» C. To inhibit corrosion | |
| 24. |
In a psychrometric chart horizontal line indicate |
| A. | Percentage humidity |
| B. | Dew point temperature |
| C. | Wet bulb temperature |
| D. | Relative humidity |
| E. | Dry bulb temperature |
| Answer» B. Dew point temperature | |
| 25. |
In a mechanical refrigeration system the highest temperature of refrigerant occurs |
| A. | Between condenser and evaporator |
| B. | In evaporator |
| C. | Before expansion valve |
| D. | Between compressor and condenser |
| E. | Before expansion valve |
| Answer» D. Between compressor and condenser | |
| 26. |
Which of the following refrigerant has the freezing point? |
| A. | Ammonia |
| B. | Carbondioxide |
| C. | Freon 11 |
| D. | Freon 22 |
| E. | All of the above |
| Answer» D. Freon 22 | |
| 27. |
Dehumidification means |
| A. | Removing humidity from a space |
| B. | Reducing the quantity of water vapour in a space |
| C. | Reducing the moisture content of a substance |
| D. | Any of the above |
| E. | None of the above |
| Answer» C. Reducing the moisture content of a substance | |
| 28. |
In a refrigeration system a condenser |
| A. | Receives liquid refrigerant and supplies liquid refrigerant |
| B. | Receives vapour refrigerant and supplies vapour refrigerant |
| C. | Receives vapour refrigerant and supplies liquid refrigerant |
| D. | Receives liquid refrigerant and supplies liquid refrigerant |
| E. | None of the above |
| Answer» C. Receives vapour refrigerant and supplies liquid refrigerant | |
| 29. |
Dry ice is |
| A. | Free from water |
| B. | Free from dissolved air or gases |
| C. | Does not contain impurities |
| D. | Solidified form of carbondioxide |
| E. | None of the above |
| Answer» D. Solidified form of carbondioxide | |
| 30. |
A refrigerating machine working on Reversed Carnot cycle takes out 2 kW per minute of heat from the system while working between temperature limits of 300?K and 200?K. The C.O.P. and power consumed by the cycle will be |
| A. | 2. 1 kW |
| B. | 1, 2 kW |
| C. | 1,1 kW |
| D. | 0, 0 kW |
| E. | 2, 2 kW |
| Answer» A. 2. 1 kW | |
| 31. |
In halide torch test if there is leakage of refrigerant, the colour of flame with change to |
| A. | Violet or orange |
| B. | Red or pink |
| C. | Blue or bright green |
| D. | Black or grey |
| E. | Yellow |
| Answer» C. Blue or bright green | |
| 32. |
If the discharge pressure of a refrigeration compressor is too high it shows |
| A. | Too little or to warm condenser water |
| B. | Lack of refrigerant |
| C. | Excessive cooling load |
| D. | Lack of compressor lubrication |
| E. | Any of the above |
| Answer» B. Lack of refrigerant | |
| 33. |
Oil separator in a refrigeration cycle is installed |
| A. | Before compressor |
| B. | Between condenser and evaporator |
| C. | Between condenser and expansion vlve |
| D. | Between compressor and condenser |
| E. | Could be installed anywhere |
| Answer» D. Between compressor and condenser | |
| 34. |
If a refrigerator compressor cuts out on starter overloads the probable reason could be |
| A. | Low line voltage |
| B. | Suction pressure high |
| C. | Discharge pressure high |
| D. | Compressor tight |
| E. | Any of the above |
| Answer» E. Any of the above | |
| 35. |
In electrolus refrigerator |
| A. | Hydrogen evaporates in ammonia |
| B. | Ammonia evaporates in hydrogen |
| C. | Hydrogen is absorbed in water |
| D. | Ammonia is absorbed in hydrogen |
| E. | Ammonia is absorbed in water |
| Answer» B. Ammonia evaporates in hydrogen | |
| 36. |
A condenser removes from the refrigerant |
| A. | Sensible heat only |
| B. | Latent heat only |
| C. | Sensile heat and latent heat |
| D. | Partly sensible heat and latent heat |
| E. | None of the above |
| Answer» A. Sensible heat only | |
| 37. |
During dehumidification process |
| A. | Relative humidity decreases |
| B. | Relative humidity does not change |
| C. | Specific humidity decreases |
| D. | Relative humidity increases |
| E. | Specific humidity increases |
| Answer» A. Relative humidity decreases | |
| 38. |
In a refrigerator evaporator is located |
| A. | Inside the refrigerator cabinet |
| B. | Adjacent to compressor |
| C. | On the side of condenser |
| D. | On the bottom of refrigerator cabinet |
| E. | Behind the refrigerator cabinet |
| Answer» A. Inside the refrigerator cabinet | |
| 39. |
In case of wet bulb depression is zero, it can be concluded that |
| A. | Rain is likely to occur |
| B. | Storm is likely to hit the place |
| C. | Relative humidity is zero |
| D. | Relative humidity is 100% |
| E. | None of the above |
| Answer» D. Relative humidity is 100% | |
| 40. |
Freon type (halocarbons) refrigerants are |
| A. | Poisonous |
| B. | Coloured |
| C. | Have peculiar odour |
| D. | Irritating |
| E. | Non-poisonous |
| Answer» E. Non-poisonous | |
| 41. |
Brine is always used as a secondary refrigerant in |
| A. | Cold storage plant |
| B. | Milk chilling plant |
| C. | Cinema hall air conditioning plants |
| D. | Ice plant |
| E. | All of the above |
| Answer» D. Ice plant | |
| 42. |
The bulk of tubes at the back of the domestic refrigerator are |
| A. | Condenser tubes |
| B. | Evaporator tubes |
| C. | Capillary tubes |
| D. | Throttling device |
| E. | Refrigerant cooling tubes |
| Answer» A. Condenser tubes | |
| 43. |
Out of the following refrigerants which one will provide highest compressor displacement per tonne of refrigeration in a vapour compression system operating between fixed temperatures |
| A. | Freon 22 |
| B. | Carbondioxide |
| C. | Freon 11 |
| D. | Freon 12 |
| E. | Ammonia |
| Answer» C. Freon 11 | |
| 44. |
Which of the following has lowest COP? |
| A. | Vapour compression cycle using wet compression |
| B. | Vapour compression cycle with superheated vapour at the end of compression |
| C. | Vapour absorption cycle |
| D. | Vapour compression cycle using dry compression |
| E. | All the refrigerants have identical specific volume |
| Answer» C. Vapour absorption cycle | |
| 45. |
The performance of an evaporative condenser largely depends on |
| A. | Wet bulb temperature |
| B. | Dry bulb temperature |
| C. | Hot water temperature |
| D. | Ambient temperature |
| E. | Air conditioned room temperature |
| Answer» A. Wet bulb temperature | |
| 46. |
The rate of evaporation of water will be low when |
| A. | Rate of evaporation does not depend on relative humidity |
| B. | Sensible heat factor |
| C. | Relative humidity is high |
| D. | Reactive humidity is zero |
| E. | Relative humidity is less than 50% |
| Answer» C. Relative humidity is high | |
| 47. |
Dry bulb temperature depends on |
| A. | Humidity of air |
| B. | Water vapour content of air |
| C. | Condition of air |
| D. | All above |
| E. | None of the above |
| Answer» E. None of the above | |
| 48. |
In a psychrometric chart vertical lines indicate |
| A. | Dew point temperature |
| B. | Dry bulb temperature |
| C. | Wet bulb temperature |
| D. | Percentage humidity |
| E. | Relative humidity |
| Answer» B. Dry bulb temperature | |
| 49. |
In case of completely dry air |
| A. | Total heat is same as latent heat |
| B. | Total heat is same as sensible heat |
| C. | Total heat is sum of sensible heat and latent heat |
| D. | Total heat is sum of sensible heat required for all individual constituents |
| E. | None of the above |
| Answer» B. Total heat is same as sensible heat | |
| 50. |
When the lower temperature is fixed, the COP of a refrigerating machine can be improved by |
| A. | Operating the machine at higher speeds |
| C. | Raising the higher temperature |
| D. | Lowering the higher temperature |
| E. | None of the above |
| Answer» D. Lowering the higher temperature | |
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