mechanical engineering MCQs – Page 211

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

mechanical engineering Mcqs

1. compressors gas turbines and jet engines 2. theory of machines 3. nuclear power plants 4. engineering materials 5. strength of materials mechanical engineering 6. thermodynamics 7. heat transfer 8. i c engines 9. steam boilers engines nozzles and turbines 10. engineering mechanics 11. fluid mechanics mechanical engineering 12. production technology 13. machine design 14. hydraulic machines 15. workshop technology 16. refrigeration and air conditioning

4201. Rating of a domestic refrigerator is of the order of__________________?
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A. 5 tons

B. 10 tons

C. 40 tons

D. 0.1 ton

E. 100 tons

4202. In vapour compression cycle the condition of refrigerant is superheated vapour _____________________?
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A. before entering the compressor

B. after passing through the expansion or throttle valve

C. after passing through the condenser

D. before passing through the condenser

E. before [entering the expansion valve

4203. Clapeyron equation is a relation between___________________?
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A. temperature, pressure, and specil volume

B. specific volume and enthalpy

C. temperature, pressure, specific volur andenthalpy

D. temperature, pressure and enthalpy

E. temperature and enthalpy

4204. The boiling point of ammonia is___________________?
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A. 33.3C

B. 33.3C

C. -50C

D. -100C

E. 0C

4205. The value of COP in vapour compression cycle is usually__________________?
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A. none of the above

B. always more than unity

C. equal to unity

D. always less than unity

E. any one of the above

4206. The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is_________________?
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A. bigger

B. smaller/bigger depending on capacity

C. unpredictable

D. smaller

E. equal

4207. A standard ice point temperature corresponds to the temperature of ___________________?
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A. mixture of ice, water and vapour under equilibrium conditions under NTP conditions

B. solid and dry ice

C. water at 0C

D. mixture of ice and water Under equilibrium conditions

E. ice at 4C

4208. The relative coefficient of performance is_____________________?
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A. 1-actual COP x theoretical COP

B. 1-actual COP/fheoretical COP.

C. actual COP/fheoretical COP

D. theoretical COP/actual COP

E. actual COP x theoretical COP

4209. Efficiency of a Carnot engine is given as 80%. If the- cycle direction be reversed, what will be the value of COP of reversed Carnot cycle_________________?
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A. 0.8

B. 0.5

C. 0.25

D. 1.25

E. none of the above

4210. The leaks in a refrigeration system using Freon are detected by____________________?
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A. halide torch which on detection produces greenish flame lighting

B. smelling

C. sulphur sticks which on detection gives white smoke

D. sensing reduction in pressure

E. using reagents

4211. Ammonia is __________________?
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A. non-inflammable

B. non-toxic

C. toxic and non-inflammable

D. none of the above

E. highly toxic and inflammable

4212. Moisture in freon refrigeration system causes________________?
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A. corrosion of whole system

B. ineffective refrigeration

C. breakdown of refrigerant

D. freezing automatic regulating valve

E. high power consumption

4213. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?
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A. takes place at constant enthalpy

B. takes place at constant pressure

C. takes place at constant temperature

D. involves no change in volume

E. takes place at constant entropy

4214. Short horizontal lines on pressure-enthalpy chart show__________________?
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A. constant volume lines

B. constant entropy lines

C. constant total heat lines

D. constant pressure lines

E. constant temperature lines

4215. An important characteristic of absorption system of refrigeration is__________________?
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A. quiet operation

B. its input only in the form of heating

C. cooling below 0C

D. noisy operation

E. very little power consumption

4216. Which of the following refrigerants has lowest freezing point_______________?
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A. Freon-22

B. Freon-12

C. NH3

D. S02

E. C02

4217. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P_____________________?
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A. none of the above

B. unpredictable

C. more

D. equally.

E. less

4218. Accumulators should have adequate volume to store refrigerant charge at least_________________?
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A. 50%

B. 25%

C. 100%

D. 10%

E. 75%

4219. In vapour compression cycle using NH3 as refrigerant, initial charge is filled at_________________?
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A. low pressure side near receiver

B. anywhere in the cycle

C. high pressure side close to receiver

D. delivery of compressor

E. suction of compressor

4220. The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will__________________?
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A. may increase or decrease depending on the type of refrigerant used

B. unpredictable

C. remain unaffected

D. increase

E. decrease

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