Refrigeration| MCQ

Refrigeration| MCQ

1. A one tonne refrigerating machine means that

(a) the total weight of the machine is one tonne.
(b) the quantity of the refrigerant used is one tonne.
(c) one tonne of water can be converted into ice.
(d) one tonne of ice when melts from and at 0°C in 24 hours, the refrigerating effect is equivalent to 14,000 kJ per hour.

2. The capacity of a refrigerating machine is expressed as

(a) inside volume of the cabinet.
(b) lowest temperature attained.
(c) gross weight of machine in tonnes.
(d) rate of abstraction of heat from the space being cooled.

3. Which of the following properties of a refrigerant is undesirable ?

(a) High critical temperature.
(b) Low specific heat of liquid.
(c) High boiling point.
(d) Low specific volume of vapor.
(e) High latent heat of vaporization.

4. Various desirable properties which should be possessed by refrigerants are

(a) non-corrosive and non-inflammability.
(b) no-toxic and freedom from objectionable odor with low working pressure.
(c) both (a) and (b).
(d) none of the above.

5. In a refrigeration cycle, the flow of refrigerant is controlled by

(a) compressor.
(b) expansion valve.
(c) condenser.
(d) evaporator.

6. Which part of the vapor compression refrigeration cycle, produces the refrigeration effect ?

(a) Evaporator.
(b) Condenser.
(c) Expansion valve.
(d) Compressor.

7. ……is used as refrigerant in a vapor absorption refrigerator.

(a) Acqua ammonia
(b) Freon
(c) Water
(d) Sulfur dioxide

8. The refrigerant Freon 12 is a compound consisting of

(a) carbon, fluorine and chlorine.
(b) carbon, chlorine and hydrogen.
(c) carbon, fluorine and hydrogen.
(d) chlorine, bromine and iodine.

9. Ammonia is preferred as a refrigerant in large commercial installations because

(a) it is non-tonic.
(b) it has a low working pressure.
(c) it is relatively cheap.
(d) it has low latent heat.

10. In a vapor compression system, which of the following units is adversely affected by the presence of moisture ?

(a) Evaporator.
(b) Expansion valve.
(c) Compressor.
(d) Condenser.

11. In a vapor absorption system lithium bromide is used as

(a) refrigerant.
(b) lubricant.
(c) absorbent.
(d) cooling substance.

12. Vapor absorption refrigeration systems have the advantage(s) of

(a) absence of moving parts.
(b) universal power source.
(c) automatic defrostration.
(d) both (a) and (b).

13. Thermoelectric refrigeration system has the advantage(s) of

(a) small initial cost.
(b) absence of moving parts.
(c) ease of automatic control by variation of magnitude of current.
(d) both (b) and (c).

14. In a domestic refrigerator, compressor and motor are assembled in a single unit known as ……….. sealed unit.

(a) hermetically
(b) homogeneously
(c) heterogeneously
(d) none of these

15. Hermetically sealed units have the advantage(s) of

(a) relatively silent operation.
(b) minimum gas leakage problem because no moving part extends through the sealing housing.
(c) minimum maintenance requirement.
(d) all of the above.

16. Which of the following motors is used in household refrigerators ?

(a) DC shunt motor.
(b) Reluctance motor.
(c) Single phase induction motor.
(d) Synchronous motor.

17. The compressor of a domestic refrigerator has been noted to run for comparatively large durations, it indicates that

(a) thermostat has become defective.
(b) the machine is overloaded.
(c) capillary tube is choked.
(d) none of the above.

18. In a refrigerator, defrosting may be done by

(a) opening the door of the refrigerator.
(b) stopping the compressor for a while.
(c) placing trays of warm waters in the refrigerator.
(d) any of the above.

19. Types of water coolers are

(a) instantaneous or pressure type.
(b) storage type.
(c) exhaust fan type.
(d) both (a) and (b).

20. Air-conditioning is the simultaneous control of……….in a confined space.

(a) temperature
(b) humidity
(c) air movement
(d) temperature, humidity, purity and movement of air

21. ……….is a process which is generally used for summer air-conditioning.

(a) Cooling with dehumidification
(b) Chemical dehumidification
(c) Adiabatic cooling
(d) Cooling with humidification

22. ………..is a process that is generally used in winter air-conditioning.

(a) Humidification
(b) Dehumidification
(c) Heating and humidification
(d) Heating and dehumidification

23. Air is dehumidified by

(a) cooling.
(b) chemical absorption.
(c) heating.
(d) both (a) and (b).

24. Compared to individual systems, the central air-conditioning system has ………… overall efficiency.

(a) higher
(b) lower
(c) same
(d) unpredictable

25. The main disadvantage(s) of central type air-conditioning s/are that

(a) dusting is very costly.
(b) absence of any individual room temperature adjustments.
(c) cigarette smoke and bacteria present in the return air from infected rooms redistribute to healthy rooms.
(d) all of the above.

26. Which of the following unitary-central systems are in common use ?

(a) Fan coil units.
(b) Induction units.
(c) All air high velocity systems.
(d) All of the above.

27. The conditions conductive to comfort depends upon

(a) humidity.
(b) temperature.
(c) air movement.
(d) air purity.
(e) all of the above factors.

Electrolytic Processes MCQ

1. The voltage required to pass the necessary current through an electrolytic cell is of the order of

(a) 1 – 2 V
(b) 10 – 20 V
(c) 100 – 120 V
(d) 150 – 200 V

2. The energy consumption for production of ammonium sulfate is of the order of

(a) 2,000 – 2,500 kWh/tonne.
(b) 3,000 – 4,000 kWh/tonne.
(c) 4,000 – 7,000 kWh/tonne.
(d) 70 – 80 kWh/tonne.

3. Materials used for copper plating are

(a) copper sulfate and sulfuric acid.
(b) copper sulfate and nitric acid.
(c) copper carbonate and ammonium carbonate.
(d) copper nitrate and sulfuric acid.

4. Materials used for chromium plating are

(a) chromium carbonate and sulfuric acid.
(b) chromic acid and sulfuric acid.
(c) chromium chloride and hydrochloride acid.
(d) none of the above.

5. The gold plating is carried out

(a) with a current density of 150 – 250 A/m² at a voltage of 1 – 2 V.
(b) with a current density of 50 – 150 A/m² at a voltage of 5 – 15 volts.
(c) with a current density of 100 – 150 A/m² at a voltage of 1 – 4 volts.
(d) with a current density of 50 – 150 A/m² at a voltage of 1 volt.

6. Power supply required for electrolytic processes is

(a) alternating current (100 – 200 A) at very low voltage (10 or 12 V).
(b) direct current (100 – 200 A) at very high voltage.
(c) direct current (100 – 200 A) at very low voltage (10 or 12 V).
(d) alternating current at very high voltage.

7. The plants for extraction and refining of metals or large scale manufacturing are located near the

(a) atomic power station.
(b) hydroelectric power station.
(c) steam power station.
(d) either atomic power station or hydroelectric power station.

8. The process of coating of a metallic surface with a harder metal by electrodepostion is called

(a) electrofacing.
(b) electroforming.
(c) electrometallisation.
(d) either (a) or (b).

9. Basically electroplating means

(a) formation of ions by two metallic plates in the acidic liquid.
(b) electrodeposition of metal on electrodes.
(c) electrodeposition of metal upon metallic surfaces.
(d) none of the above.

10. Electroplating is done for

(a) replacement of worn out material.
(b) protection of metals against corrosion.
(c) giving a shining appearance to articles.
(d) all of the above.

11. The preparation of an object for electroplating involves the

(a) removal of oil, grease or other organic material.
(b) removal of rust, scale, oxides, or other inorganic coatings adhering to the metal.
(c) mechanical preparation of the metal surface by polishing, buffing etc
(d) any or all of the above operations.