MCQOPTIONS
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MCQOPTIONS
This section includes 197 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Leakage past the piston rings and valve seats in I.C. engines with increase in speed_______________? |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | unpredictable |
| E. | none of the above |
| Answer» C. remains same | |
| 102. |
Kerosene is distilled at________________? |
| A. | 30 – 65°C |
| B. | 65 – 220°C |
| C. | 220 – 350°C |
| D. | 350 – 450°C |
| E. | 450-550°C |
| Answer» D. 350 – 450°C | |
| 103. |
It the temperature of intake air in IC engines is lowered, then its efficiency will_______________________? |
| A. | increase |
| B. | decrease |
| C. | remain same |
| D. | increase upto certain limit and then decrease |
| E. | decrease upto certain limit and then in-crease |
| Answer» B. decrease | |
| 104. |
Iso-oct ,ne________________? |
| A. | has octane number of 0 |
| B. | has octane number of 50 |
| C. | has octane number of 100 |
| D. | is an index of detonation quality |
| E. | is an index of knocking quality |
| Answer» D. is an index of detonation quality | |
| 105. |
Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power_____________? |
| A. | upto 25% |
| B. | upto 35% |
| C. | upto 50% |
| D. | upto 75% |
| E. | upto 100%. |
| Answer» F. | |
| 106. |
Injection lag is_________________? |
| A. | the time taken by fuel after injection (before top dead center) to reach upto auto-ignition temperature |
| B. | time before actual fuel injection and the pump pluger starts to pump fuel |
| C. | time corresponding to actual injection and top dead center |
| D. | time corresponding to actual ignition and top dead center |
| E. | none of the above |
| Answer» C. time corresponding to actual injection and top dead center | |
| 107. |
In turbulence chamber in diesel engine__________________? |
| A. | the shape and layout of the piston crown, the inlet port, and the valve produce the turbulent effect of fuel mixture |
| B. | fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat |
| C. | only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency |
| D. | there are no valves |
| E. | fuel is partly burnt by spark |
| Answer» C. only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency | |
| 108. |
In the opposed piston diesel engine, the combustion chamber is located________________? |
| A. | above the piston (/;) below the piston |
| B. | between the pistons |
| C. | any when |
| D. | there is no such criterion |
| Answer» C. any when | |
| 109. |
In the crankcase method of scavenging, the air pressure is produced by_________________? |
| A. | supercharger |
| B. | centrifugal pump |
| C. | natural aspirator |
| D. | movement of engine piston |
| E. | reciprocating pump |
| Answer» E. reciprocating pump | |
| 110. |
In the case of petrol engine at maximum output, the percentage of CO in exhaust gases is ____________________? |
| A. | Zero |
| B. | 5-10% |
| C. | Depends on load and quality of fuel |
| D. | Considerable percent |
| Answer» E. | |
| 111. |
In the case of compression ignition engine, the %age of CO in exhaust gases is________________? |
| A. | Zero |
| B. | 5-10% |
| C. | Depends on load |
| D. | Considerable percent |
| Answer» B. 5-10% | |
| 112. |
In precombustion chamber in diesel engine________________? |
| A. | The shape and layout of the pistion crown, the inlet port, and the valve produce the turbulent effect of fuel mixture |
| B. | Fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat |
| C. | Only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency |
| D. | There are no valves |
| Answer» D. There are no valves | |
| 113. |
In petrol engines, the maximum power is developed corresponding to relative fuel air ratio of________________? |
| A. | 0.85 |
| B. | 1 |
| C. | 1.1 to 1.3 |
| D. | 1.2 to 1.5 |
| Answer» D. 1.2 to 1.5 | |
| 114. |
In petrol engines, advancing the spark timing will_______________? |
| A. | increase the knocking tendency |
| B. | decrease the knocking tendency |
| C. | not affect the knocking tendncy |
| D. | increase or decrease knocking tendency depending on strenght and time of spark |
| E. | unpredictable |
| Answer» B. decrease the knocking tendency | |
| 115. |
In petrol engine using a fixed octane rating fuel and fixed compression ratio, super charging will_________________? |
| A. | increase the knocking tendency |
| B. | decrease the knocking tendency |
| C. | not affect the knocking tendency |
| D. | increase or decrease knocking tendency depending on strength and time of spark |
| E. | unpredictable |
| Answer» B. decrease the knocking tendency | |
| 116. |
In petrol engine, increase of cooling water temperature will_________________? |
| A. | increase the knocking tendency |
| B. | decrease the knocking tendecny |
| C. | not affect the knocking tendency |
| D. | increase or decrease knocking tendency depedning on strength and time of spark |
| E. | unpredictable |
| Answer» B. decrease the knocking tendecny | |
| 117. |
In order to prevent knock in the S.I. engines, the charge away from the spark plug should have___________________? |
| A. | low temperature |
| B. | low density |
| C. | long ignition delay |
| D. | rich mixture |
| E. | all of the above |
| Answer» F. | |
| 118. |
In order to prevent formation of carbon on the injector, the temperature of nozzle tip should be__________________? |
| A. | less than 100°C |
| B. | between 100-250°C |
| C. | between 250 – 300°C |
| D. | between 400 – 500°C |
| E. | between 500 – 1000°C |
| Answer» D. between 400 – 500°C | |
| 119. |
In open combustion chamber in diesel engines____________________? |
| A. | the shape and layout of the piston crown, the inlet port, and the valve produce the turbulent effect on fuel mixture |
| B. | fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat |
| C. | only a part of air charge is contained in an auxiliary chamber in which the fuel starts to burn with insufficient air which due to explosion tendency |
| D. | fuel is injected at atmospheric pres¬sure |
| E. | there are no valves |
| Answer» B. fuel is injected into an auxiliary chamber that is separated from the cylinder by an orifice or throat | |
| 120. |
In loop scavenging, the top of the piston is________________? |
| A. | flat |
| B. | contoured |
| C. | slanted |
| D. | depressed |
| E. | convex shaped |
| Answer» C. slanted | |
| 121. |
In isochronous governing, speed droop is_______________? |
| A. | 100% |
| B. | 50% |
| C. | 5% |
| D. | 30% |
| E. | 1%. |
| Answer» E. 1%. | |
| 122. |
In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of____________________? |
| A. | 250°C |
| B. | 500°C |
| C. | 1000°C |
| D. | 150CPC |
| E. | 2000°C |
| Answer» D. 150CPC | |
| 123. |
In diesel engine, the compression ratio in comparison to expansion ratio is_______________? |
| A. | same |
| B. | less |
| C. | more |
| D. | variable |
| E. | more/less depending on engine capacity |
| Answer» D. variable | |
| 124. |
In case of gas turbines, the gaseous fuel consumption guarantees are based on________________? |
| A. | high heat value |
| B. | low heat value |
| C. | net calorific value |
| D. | middle heat value |
| E. | calorific value |
| Answer» C. net calorific value | |
| 125. |
In carburettors, the top of the fuel jet with reference to the level in the float chamber is kept at_________________? |
| A. | same level |
| B. | slightly higher level |
| C. | slightly lower level |
| D. | may be anywhere |
| E. | varies from situation to situation |
| Answer» C. slightly lower level | |
| 126. |
In a typical medium speed 4 stroke cycle diesel engine_______________? |
| A. | exhaust valve opens at 35° before bot-tom dead center and closes at 20° after top dead center |
| B. | exhaust valve opens at bottom ‘dead center and closes at top dead center |
| C. | exhaust valve opens just after bottom dead center and closes just before top dead center |
| D. | may open and close anywhere |
| E. | none of the above is true |
| Answer» B. exhaust valve opens at bottom ‘dead center and closes at top dead center | |
| 127. |
In a typical medium speed 4-stroke cycle diesel engine________________? |
| A. | compression starts at 35° after bottom dead center and ends at top dead center |
| B. | compression starts at bottom dead center and ends at top dead center |
| C. | compression starts at 10° before bottom dead center and, ends just before top dead center |
| D. | may start and end anywhere |
| E. | none of the above |
| Answer» B. compression starts at bottom dead center and ends at top dead center | |
| 128. |
In a typical medium speed, 4-stroke cycle diesel engine ___________________? |
| A. | fuelinjection starts at 10° before to dead center and ends at 20° after tor dead center |
| B. | fuel injection starts at top dead center and ends at 20° after top dead center |
| C. | fuel injection starts at just before top dead center and ends just after top deac center |
| D. | may start and end anywhere |
| E. | none of the above |
| Answer» B. fuel injection starts at top dead center and ends at 20° after top dead center | |
| 129. |
In a typical medium speed 4-stroke cycle diesel engine the inlet valve_____________________? |
| A. | opens at 20° before top dead center and closes at 35° after the bottom dead center |
| B. | opens at top dead center and closes at bottom dead center |
| C. | opens at 10° after top dead center and closes 20° before the bottom dead center |
| D. | may open or close anywhere |
| E. | remains open for 200° |
| Answer» B. opens at top dead center and closes at bottom dead center | |
| 130. |
In a naturally aspirated diesel engine, the air is supplied by________________? |
| A. | a supercharger |
| B. | a centrifugal blower |
| C. | a vacuum chamber |
| D. | an injection tube |
| E. | forced chamber |
| Answer» D. an injection tube | |
| 131. |
In a diesel engine, the fuel is ignited by___________________? |
| A. | spark |
| B. | injected fuel |
| C. | heat resulting from compressing air that is supplied for combustion |
| D. | ignition |
| E. | combustion chamber |
| Answer» D. ignition | |
| 132. |
In a diesel engine, injection pressure developed by injector is of the order of______________? |
| A. | 10 kg/cm2 |
| B. | 100 kg/cm2 |
| C. | 500 kg/cm2 |
| D. | 1400 kg/cm2 |
| Answer» E. | |
| 133. |
In a cycle, the spark lasts roughly for ____________________? |
| A. | 1 sec |
| B. | 0.1 sec |
| C. | 0.01 sec |
| D. | 0.001 sec |
| E. | 0.0001 sec |
| Answer» E. 0.0001 sec | |
| 134. |
Ignition timing of a multicylider petrol engine can be adjusted by_________________? |
| A. | rotating the crank |
| B. | adjusting the spark plug gap |
| C. | adjusting ignition coil position |
| D. | rotating the distributor |
| E. | delaying the spark by increasing capacitor in ignition circuit |
| Answer» E. delaying the spark by increasing capacitor in ignition circuit | |
| 135. |
Ignition quality of diesel-fuel oil is expressed by an index called__________________? |
| A. | octane number |
| B. | cetane number |
| C. | calorific value |
| D. | carbon content |
| E. | ignition temperature |
| Answer» C. calorific value | |
| 136. |
Ignition quailty of petrol is expressed by___________________? |
| A. | octane number |
| B. | cetane number |
| C. | calorific value |
| D. | self ignition temperature |
| E. | distillation temperature |
| Answer» B. cetane number | |
| 137. |
Ignition lag is__________________? |
| A. | the time taken by fuel after injection (before top dead center) to reach upto auto-ignition temperature |
| B. | time before actual fuel injection and the pump plunger starts to pump fuel |
| C. | time corresponding to actual injection and top dead center |
| D. | time corresopnding to actual ingition and top dead center |
| E. | none of the above |
| Answer» B. time before actual fuel injection and the pump plunger starts to pump fuel | |
| 138. |
If the intake air temperature of I.C. engine increases, its efficiency will_________________? |
| A. | increase |
| B. | decrease |
| C. | remain same |
| D. | unpredictable |
| E. | depend on other factors |
| Answer» C. remain same | |
| 139. |
If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be________________? |
| A. | 2% |
| B. | 4% |
| C. | 8% |
| D. | 14% |
| E. | 27%. |
| Answer» E. 27%. | |
| 140. |
If petrol is used in a diesel engine, then______________? |
| A. | higher knocking will occur |
| B. | efficiency will be low |
| C. | low power will be produced |
| D. | black smoke will be produced |
| E. | lot of fuel will remain unburnt |
| Answer» B. efficiency will be low | |
| 141. |
If overhead clearance is less, then the following type of engine should be selected__________________? |
| A. | V-type |
| B. | In-line |
| C. | Vertical |
| D. | Horizontal |
| E. | Radial |
| Answer» E. Radial | |
| 142. |
If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the________________? |
| A. | exhaust will be smoky |
| B. | piston rings would stick into piston grooves |
| C. | exhaust temperature will be high |
| D. | engine starts overheating |
| E. | scavenging occurs |
| Answer» F. | |
| 143. |
If diesel is fed by mistake in the oil tank of a petrol engien, then engine will________________? |
| A. | give lot of smoke |
| B. | detonate |
| C. | knock |
| D. | not run |
| E. | run for some time and then stop |
| Answer» E. run for some time and then stop | |
| 144. |
Hot air standard diesel cycle efficiency with increase in value of C„_______________? |
| A. | increases |
| B. | decreases |
| C. | remains unaffected |
| D. | depends on other factors |
| E. | unpredictable |
| Answer» C. remains unaffected | |
| 145. |
High carbon content in diesel oil used for diesel engine leads to_________________? |
| A. | production of highly corrosive gases corroding the cylinder walls and exhaust system |
| B. | excessive engine wear |
| C. | damaging of both the storage tank and the engine |
| D. | deposition on engine parts |
| E. | none of the above |
| Answer» E. none of the above | |
| 146. |
Gaseous-fuel guarantees are based on___________________? |
| A. | calorific value of oil |
| B. | low heat value of oil |
| C. | high heat value of oil |
| D. | mean heat value of oil |
| E. | all of the above |
| Answer» C. high heat value of oil | |
| 147. |
Fuel oil consumption guarantees for I .C. engine are usually based on__________________? |
| A. | low heat value of oil |
| B. | high heat value of oil |
| C. | net calorific value of oil |
| D. | calorific value of fuel |
| E. | all of the above |
| Answer» C. net calorific value of oil | |
| 148. |
Fuel consumption with increase in back pressure will________________? |
| A. | increase |
| B. | decrease |
| C. | remain unaffected |
| D. | depend on other factors |
| E. | none of the above |
| Answer» B. decrease | |
| 149. |
Fuel consumption of diesef engines is not guaranteed at one quarter load because at such low loads________________? |
| A. | the friction is high |
| B. | the friction is unpredictable |
| C. | the small difference in cooling water temperature or in internal friction has a disproportionate effect |
| D. | the engine is rarely operated |
| E. | none of the above |
| Answer» D. the engine is rarely operated | |
| 150. |
Freezing temperature of petrol is usually__________________? |
| A. | 0°C |
| B. | – 10°C |
| C. | 10°C |
| D. | less than – 30°C |
| E. | less than – 273°C |
| Answer» E. less than – 273°C | |