mechanical engineering MCQs – Page 105

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 Review each marked answer and report any item that may be outdated or unclear.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

2081. The heat loss in a boiler takes place in the form of________________?
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A. moisture present in fuel and steam formed by combustion of hydrogen in fuel

B. radiation

C. all of the above

D. heat carried away by ash

E. heat carried away by flue gases

2082. Sulphur in coal results in___________________?
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A. all of the above

B. causing clinkering and slagging

C. facilitating ash precipitation

D. spontaneous combustion during coal storage

E. corroding air heaters

2083. Spontaneous combustion is a phenomenon in which____________________?
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A. all the fuel burns instantaneously producing high energy release

B. fuel burns with less air

C. none of the above

D. explosion in furnace

E. coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal

2084. Thermal efficiency of a thermal power plant is of the order of___________________?
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A. 20%

B. 15%

C. 45%

D. 30%

E. 60%.

2085. An economiser in a boiler______________________?
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A. decreases fuel consumption

B. decreases steam pressure

C. increases steam flow

D. increases steam pressure

E. increases life of boiler

2086. Ball valves are commonly used to_________?
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A. check flow

B. change flow direction

C. start/stop flow

D. throttle flow

2087. The radius of a dished head is taken approximately as______________________?
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A. one

B. half

C. one-fourth

D. three

E. two

2088. Overfire burning is the phenomenon of _____________________?
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A. fuel bed firing

B. supply of excess, air

C. supply of excess coal

D. none of the above

E. burning CO and unburnts in upper zone of furnace by supplying more air

2089. What is the most common valve used in piping systems to throttle or regulate flow ?
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A. Gate valve

B. Globe valve

C. Butterfly valve

D. Plug valve

2090. The maximum discharge through a chimney occurs when the height of chimney is_____________________?
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A. more than the tallest building nearby

B. infinitely long

C. around 200 meters

D. equal to the height of the hot gas column producing draught

E. outside temperature is very low

2091. The average calorific value of wood is about : __________?
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A. 23000 kj/kg

B. 33500 kj/kg

C. 19700 kj/kg

D. 25000 kj/kg

2092. Film boling occurs at _______________________?
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A. very low pressure

B. none of the above

C. very high pressures

D. medium pressures

E. atmospheric pressures

2093. The function of injector used in small capacity boilers is to____________________?
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A. pump water, similar to boiler feed pump

B. add make up water in the system

C. create vacuum

D. none of the above

E. inject chemical solution in feed pump

2094. In which of the following boilers, the draught in furnace is increased by utilising exhaust steam from engine__________________?
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A. locomotive boiler

B. benson boiler

C. lancashire boiler

D. babcock and wilcox boiler

E. cochran boiler

2095. In forced circulation type boiler__________________?
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A. water is heated in a large number of tubes

B. water is supplied in drum and through down-comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

C. heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

D. water is converted into steam in one pass without any recirculation

E. feed pump is employed to supplement natural circulation in water wall type furnace

2096. The three Ts for good combustion are____________________?
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A. temperature, time, and turbulance

B. thorough mixing, total air, and temperature

C. total air, time, and temperature

D. total air, true fuel, and turbulance

E. none of the above

2097. Pour point of fuel oil is the____________________?
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A. storage temperature

B. lowest temperature at which oil will flow under set condition