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MCQOPTIONS
This section includes 205 Mcqs, each offering curated multiple-choice questions to sharpen your Refrigeration and Air conditioning knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
In a vapour compression refrigeration cycle, high head pressure is indicated which does not change even when compressor is stopped and allowed to cool. The probable cause may be |
| A. | High refrigerant charge |
| B. | Low refrigerant charge |
| C. | Air in the system |
| D. | High vapour pressure |
| E. | Any of the above |
| Answer» D. High vapour pressure | |
| 152. |
In a vapour compression cycle the lowest temperature occurs in |
| A. | Evaporator |
| B. | Expansion valve |
| C. | Condenser |
| D. | Receiver |
| E. | Compressor |
| Answer» B. Expansion valve | |
| 153. |
In a vapour compression refrigeration cycle using ammonia as a refrigerant the temperature of ammonia after compression will be at the range |
| A. | 40?C to 0?C |
| B. | 70?C to - 110?C |
| C. | 0?C to - 15?C |
| D. | ? 15?C to - 40?C |
| E. | 50?C to 40?C |
| Answer» C. 0?C to - 15?C | |
| 154. |
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» E. All of the above | |
| 155. |
When ammonia is the refrigerant, which of the following will be be the material for pipe through which refrigerant flows? |
| A. | Cast steel or wrought iron |
| B. | Copper |
| C. | PVC |
| D. | Brass |
| E. | Aluminium |
| Answer» B. Copper | |
| 156. |
During compression in a vapour compression cycle of the refrigerant is super heated |
| A. | C.O.P. is reduced |
| B. | C.O.P. is increased |
| C. | Work done is reduced |
| D. | Refrigerating effect is reduced |
| E. | None of the above |
| Answer» B. C.O.P. is increased | |
| 157. |
In vapour compression cycle the highest temperature of the refrigerant during the cycle occurs |
| A. | After expansion valve |
| B. | After evaporator |
| C. | After condenser |
| D. | After compression |
| E. | None of the above |
| Answer» E. None of the above | |
| 158. |
In a vapour absorption refrigeration system the power is required for vapour compressor as compared to that in vapour compression cycle is |
| A. | More |
| B. | Less |
| C. | There is no such relation |
| D. | One forth |
| E. | Half |
| Answer» D. One forth | |
| 159. |
In a vapour absorption system as compared to vapour compression system, the compressor is replaced by |
| A. | Receiver |
| B. | Expansion valve |
| C. | Evaporator |
| D. | Conderser |
| E. | Absorber and generator |
| Answer» F. | |
| 160. |
The condension of moisture contained in air will take place at |
| A. | Any where between dry bulb temperature and wet bulb temperature |
| B. | Dew point temperature |
| C. | Dry bulb temperature |
| D. | Wet bulb temperature |
| E. | Saturation temperature |
| Answer» C. Dry bulb temperature | |
| 161. |
A cooling tower cools water |
| A. | Below wet bulb temperature |
| B. | Equal to wet bulb temperature |
| C. | Slightly above wet bulb temperature |
| D. | Wet bulb has no bearing on cooling load performance |
| E. | None of the above |
| Answer» D. Wet bulb has no bearing on cooling load performance | |
| 162. |
If the suction pressure of a refrigeration compressor is too high, it shows |
| A. | Lack of refrigerant on cycle |
| B. | Excessive load and evaporator |
| C. | Negligible load on evaporator |
| D. | Any of above |
| E. | None of the above |
| Answer» C. Negligible load on evaporator | |
| 163. |
The statement that molecular weight of all gases occupy the same volume at NTP is known as |
| A. | First law of thermodynamics |
| B. | Joules law |
| C. | Charle's law |
| D. | Avogadro's law |
| E. | Dalton's law |
| Answer» E. Dalton's law | |
| 164. |
When the air temperature reaches the point where relative humidity is 100% the air is saturated because it cannot hold any more moisture. This temperature is called |
| A. | Freezing point |
| B. | Partial freezing point |
| C. | Dew point of air |
| D. | Dew point |
| E. | Dew point of water vapour |
| Answer» E. Dew point of water vapour | |
| 165. |
The secondary refrigerant used in milk chilling plants is usually |
| A. | Brine |
| B. | Ammonia solution |
| C. | Glycol |
| D. | Sodium silicate |
| E. | Any of the above |
| Answer» D. Sodium silicate | |
| 166. |
Hydrogen cannot be liquefied at room temperature by the application of pressure, because |
| A. | It is a diatomic molecule |
| B. | It has high viscosity |
| C. | Its critical temperature is lower than the normal room temperature |
| D. | Its thermal conductivity is high |
| E. | It has low density |
| Answer» D. Its thermal conductivity is high | |
| 167. |
The condition of refrigerant before and after the expansion or throttle valve in a vapour compression system is |
| A. | Wet vapour, very wet vapour |
| B. | Wet vapour, dry vapour |
| C. | High pressure saturated liquid, very wet vapour |
| D. | Very wet vapour, high pressure, saturated liquid |
| E. | None of the above |
| Answer» D. Very wet vapour, high pressure, saturated liquid | |
| 168. |
The crankcase explosion of a refrigeration compressor |
| A. | Occurs due to ignition of vapours in compressor crank case |
| B. | Occurs when load is too high |
| C. | Means breakdown in compression |
| D. | Occurs between piston and cylinder heads |
| E. | Means ignition of refrigeration due to high temperature |
| Answer» B. Occurs when load is too high | |
| 169. |
If a discharge pressure of a refrigeration compressor is too high, it shows there is (are) |
| A. | Too little or too warm condenser water |
| B. | Fouled tubes in shell and tube condenser |
| C. | Improper operations of evaporator condenser |
| D. | Overcharge of refrigerant |
| E. | Any of the above |
| Answer» F. | |
| 170. |
The function of desuperheating coil in a condenser is |
| A. | To remove heat from condenser |
| B. | To improve performance of a condenser |
| C. | To discharge the heat exchanged in condenser to the surroundings |
| D. | To remove the heat of superheat of the refrigerant before it enters the condenser |
| E. | None of the above |
| Answer» E. None of the above | |
| 171. |
An increase in the movement of the molecules within a solid, liquid or gas corresponds to |
| A. | A drop in temperature |
| B. | No change in temperature |
| C. | Latent heat addition/removal |
| D. | A rise in temperature |
| E. | None of the above |
| Answer» E. None of the above | |
| 172. |
A storage tank which receives liquid refrigerant from evaporator and prevents it from flowing into suction line is known as |
| A. | Accumulator |
| B. | Agitator |
| C. | Balancer |
| D. | Condenser |
| E. | None of the above |
| Answer» B. Agitator | |
| 173. |
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. | 1 kW |
| B. | 1, 2 kW |
| C. | 1,1 kW |
| D. | 0, 0 kW |
| E. | 2, 2 kW |
| Answer» B. 1, 2 kW | |
| 174. |
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» F. | |
| 175. |
While designing air conditioning system for a theatre the various heat loads are categorized as given below. Which one will give lowest heat load? |
| A. | Lights |
| B. | Neither absorbs nor discards heat |
| C. | Outside temperature in summer |
| D. | Human beings |
| E. | Direct sun |
| Answer» B. Neither absorbs nor discards heat | |
| 176. |
When Freon 12 is the refrigerant, the condenser and evaporator cables are made of |
| A. | Aluminium |
| B. | Cast iron |
| C. | Steel |
| D. | Copper |
| E. | Wrought iron |
| Answer» E. Wrought iron | |
| 177. |
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» B. Dry bulb temperature | |
| 178. |
PVC tubes are used for condenser and evaporator when the refrigerant is |
| A. | Freon 12 |
| B. | Freon 22 |
| C. | Ammonia |
| D. | Sulphur dioxide |
| E. | None of the above |
| Answer» F. | |
| 179. |
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» B. Adjacent to compressor | |
| 180. |
Class II group of refrigerants absorb sensible heat while giving refrigeration effect. Which of the following is a class II refrigerant |
| A. | Ammonia |
| B. | Carbondioxide |
| C. | Freon 12 |
| D. | Methyl chloride |
| E. | All of the above |
| Answer» E. All of the above | |
| 181. |
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» D. Lowering the higher temperature | |
| 182. |
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» E. None of the above | |
| 183. |
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» D. Offer no resistance to flow of heat at low temperatures | |
| 184. |
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» D. Specific humidity | |
| 185. |
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» D. Anammonia and a water solution | |
| 186. |
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» D. Evaporator | |
| 187. |
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» B. Bellows | |
| 188. |
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» B. 0.5 kg | |
| 189. |
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» D. To prevent scale formation | |
| 190. |
Refrigerant No. 717 is |
| A. | Ammonia |
| B. | Freon 12 |
| C. | Carbondioxide |
| D. | Freon 22 |
| E. | Methyl chloride |
| Answer» B. Freon 12 | |
| 191. |
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» E. None of the above | |
| 192. |
pH value of a brine solution is |
| A. | More than |
| B. | 14 |
| C. | 70 |
| D. | Less than 7 |
| E. | Could be any value |
| Answer» F. | |
| 193. |
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» C. Wet bulb temperature | |
| 194. |
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» D. Any of the above | |
| 195. |
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» D. 5 | |
| 196. |
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» E. Before expansion valve | |
| 197. |
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» D. remains constant always | |
| 198. |
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» C. Freon 12 | |
| 199. |
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» C. Freon 11 | |
| 200. |
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» C. Depends on other conditions | |