mechanical engineering MCQs – Page 15

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 Review each marked answer and report any item that may be outdated or unclear.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

281. The advantage of multistage compression over single stage compression is ________________?
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A. higher volumetric efficiency

B. lower power consumption per unit of air delivered

C. decreased discharge temperature

D. moisture free air

E. all of the above

282. Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm . The air pressure will be_____________________ ?
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A. 1.03 kg/cm2

B. 1.06 kg/cm2

C. 0.53 kg/cm2

D. 0.5 kg/cm2

E. 1.00 kg/cm2

283. Gas turbines for power generaion are normally used___________________?
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A. to supply peak load requirements

B. to supply base load requirements

C. when other sources of power fail

D. in emergency

E. to enable start thermal power plant

284. The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio_____________________?
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A. increases

B. remains same

C. first decreases and then increases

D. decreases

E. first increases and then decreases

285. Medium specific speea of turbine implies it is___________________?
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A. impulse turbine

B. none of the above

C. Francis turbine

D. propeller turbine

E. any one of the above

286. The fast breeder reactor uses the following moderator__________________?
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A. heavy water

B. no moderator is used

C. carbon dioxide

D. graphite

E. demineralised water

287. Reheating in multistage expansion gas turbine results in____________________?
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A. reduction in compressor work

B. maximum work output

C. high thermal efficiency

D. none of the above

E. decrease of heat loss in exhaust

288. The horse power required in above case will be___________________?
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A. none of the above

B. same

C. 0.75 B.H.P.

D. 1.5 B.H.P.

E. B.H.P./0.75

289. In spot welding, the spacing between two spot weld should not be less than _______________?
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A. 3d

B. d

C. 1.5d

D. 6d

290. The most commonly used moderator in nuclear plants is___________________?
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A. graphite and concrete

B. heavy water

C. graphite

D. deutrium

E. concrete and bricks

291. The optimum value of vane exit angle for a centrifugal pump impeller is_________________?
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A. 10-15

B. 80-90.

C. 30-40

D. 50-60

E. 20-25

292. Phenomenon of choking in compressor means __________________?
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A. increased inclination of chord with air steam

B. does not occur

C. no flow of air

D. reducing mass flow rate with increase in pressure ratio

E. fixed mass flow rate regardless of pressure ratio

293. Which is false statement about advantages of multistage compressor in comparison to single stage compressor_________________?
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A. better mechanical balance

B. lower volumetric efficiency

C. less power requirement

D. more effective lubrication

E. less loss of air due to leakage past the cylinder

294. In the axial flow gas turbine, the work ratio is the ratio of____________________?
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A. output and input

B. none of the above

C. actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet

D. compressor work and turbine work

E. actual compressor work and theoretical comprssor work

295. The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the_____________________?
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A. total adiabaitc temperature drop

B. total temperature drop in the stage

C. total temperature drop

D. difference of maximum and minimum temperature in the cycle

E. adiabatic temperature drop in the stage

296. Open cycle gas turbine works on___________________?
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A. ankine cycle

B. Carnot cycle

C. Brayton or Atkinson cycle

D. Joule cycle

E. Erricsson cycle

297. One gram of uranium will produce energy equivalent to approximately____________________?
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A. 1 tonne of high grade coal

B. 4.5 tonnes of high grade coal

C. 100 tonnes of high grade coal

D. 10 tonnes of high grade coal

E. 1000 tonnes of high grade coal

298. Medium specific speed of a pump implies it is_________________?
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A. none of the above

B. centrifugal pump

C. mixed flow pump

D. axial flow pump

E. any one of the above

299. The compressor performance at higher altitude compared to sea level will be _______________?
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A. same

B. higher

C. lower

D. none of the above

E. dependent on other factors

300. In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of__________________?
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A. liquid hydrogen

B. atmospheric air

C. oxygen alone

D. compressed air

E. vacuum

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