MCQOPTIONS
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MCQOPTIONS
This section includes 513 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Engine can be fired with |
| A. | solid fuel |
| B. | liquid fuel |
| C. | gaseous fuel |
| D. | any of the above fuels |
| Answer» E. | |
| 2. |
Excess quantities of sulphur in diesel fuel are Objectionable because it may cause thefollowing |
| A. | piston ring and cylinder wear |
| B. | formation of hard coating on piston skirts |
| C. | oil sludge in the engine crank case |
| D. | detonation |
| Answer» E. | |
| 3. |
Desirable characteristics of the combustion chamber for SI engines to avoid knock is |
| A. | small bore |
| B. | short ratio of fame path to bore |
| C. | absence of hot surfaces in the last region of the charge |
| D. | all of the above |
| Answer» E. | |
| 4. |
For the same peak pressure and work output |
| A. | ƞOtto > ƞDual > ƞDiesel |
| B. | ƞOtto > ƞDiesel > ƞDual |
| C. | ƞDiesel > ƞOtto > ƞDual |
| D. | ƞDiesel > ƞDual > ƞOtto |
| Answer» E. | |
| 5. |
In the air box method of measuring air flow, the air box is provided to |
| A. | have constant temperature |
| B. | have constant flow |
| C. | damp out the pulsations |
| D. | provide constant velocity of flow |
| Answer» D. provide constant velocity of flow | |
| 6. |
Dissociation can be considered as |
| A. | disintegration of combustion products at high temperature |
| B. | reverse process of combustion |
| C. | heat absorption process |
| D. | all of the above |
| Answer» E. | |
| 7. |
D-MPFI system uses |
| A. | port injection |
| B. | manifold injection |
| C. | direct injection |
| D. | throttle body injection |
| Answer» C. direct injection | |
| 8. |
In an actual SI engine the pumping loss with respect to speed |
| A. | decreases |
| B. | Increases |
| C. | remains constant |
| D. | nothing to do with speed |
| Answer» C. remains constant | |
| 9. |
Advantage of fuel injection in SI engine is |
| A. | low initial cost |
| B. | low maintenance requirements |
| C. | increased volumetric efficiency |
| D. | none of the above |
| Answer» D. none of the above | |
| 10. |
For a four cylinder vertical engine, the commonly used firing order is |
| A. | 1-2-3-4 |
| B. | 3-4-1-2 |
| C. | 1-3-4-2 |
| D. | 4-3-2-1 |
| Answer» D. 4-3-2-1 | |
| 11. |
With dissociation peak temperature is obtained |
| A. | at the stoichiometric air-fuel ratio |
| B. | when the mixture is slightly lean |
| C. | when the mixture is slightly rich |
| D. | none of the above |
| Answer» D. none of the above | |
| 12. |
For what purpose is the Rhodium used? |
| A. | To reduce CO and HC |
| B. | To reduce NOx |
| C. | To reduce CO |
| D. | To reduce HC |
| Answer» C. To reduce CO | |
| 13. |
For the same compression ratio and heat addition |
| A. | ƞOtto > ƞDiesel > ƞDual |
| B. | ƞDiesel > ƞOtto > ƞDual |
| C. | ƞOtto> ƞDual > ƞDiesel |
| D. | ƞDual> ƞDiesel > ƞOtto |
| Answer» D. ƞDual> ƞDiesel > ƞOtto | |
| 14. |
Mist lubrication system is mainly used in |
| A. | four-stroke petrol engine |
| B. | four-stroke diesel engine |
| C. | two-stroke petrol engine |
| D. | Wankle engine |
| Answer» D. Wankle engine | |
| 15. |
CO in the exhaust of a car engine should not be more than: |
| A. | 0.5% |
| B. | 2% |
| C. | 5% |
| D. | 10% |
| Answer» B. 2% | |
| 16. |
‘MPFI’ stands for |
| A. | Multi point fuel injection |
| B. | Multi port fuel injection |
| C. | Manifold point fuel injection |
| D. | Manifold port fuel injection |
| Answer» B. Multi port fuel injection | |
| 17. |
The rating of a diesel engine, with increase in air-intlet temperature, will |
| A. | increase linearly |
| B. | decrease linearly |
| C. | increase parabolically |
| D. | decrease parabolically |
| Answer» C. increase parabolically | |
| 18. |
Ignition quality of diesel fuel is indicated by its |
| A. | octane number |
| B. | cetane number |
| C. | fash point |
| D. | fire point |
| Answer» C. fash point | |
| 19. |
For dual combustion cycle for fixed value of heat addition and compression ratio |
| A. | mep wil be greater with increase in rp, and decrease in rc |
| B. | mep will be greater with decrease in rp and decrease in rc |
| C. | mep remain the same with increase in rp and decrease in rc |
| D. | none of the above |
| Answer» B. mep will be greater with decrease in rp and decrease in rc | |
| 20. |
The secondary winding of ignition coil consists of |
| A. | few turns of fine wire |
| B. | few turns of thick wire |
| C. | many turns of fine wire |
| D. | many turns of thick wire |
| Answer» D. many turns of thick wire | |
| 21. |
Dwell period |
| A. | is directly proportional to engine speed |
| B. | is inversely proportional to engine speed |
| C. | does not depend on engine speed |
| D. | none of the above |
| Answer» C. does not depend on engine speed | |
| 22. |
Olefins are represented by the formula |
| A. | CnH2n |
| B. | CnH2n+2 |
| C. | CnH2n-4 |
| D. | CnH2n-6 |
| Answer» B. CnH2n+2 | |
| 23. |
The normal range of compression ratio for Diesel cycle is |
| A. | 4 to 6 |
| B. | 6 to 8 |
| C. | 15 to 20 |
| D. | >25 |
| Answer» D. >25 | |
| 24. |
Maximum allowable hydrocarbon in the car emission are approximately |
| A. | 10 ppm |
| B. | 100 ppm |
| C. | 1000 ppm |
| D. | 5000 ppm |
| Answer» C. 1000 ppm | |
| 25. |
A perfect engine works on the Carnot cycle between 727 °C and 227°C. The efficiency of the engine is |
| A. | 0.5 |
| B. | 0.75 |
| C. | 1 |
| D. | 0.25 |
| Answer» B. 0.75 | |
| 26. |
for the same compression ratio and heat rejection, |
| A. | ƞOtto> ƞDual > ƞDiesel |
| B. | ƞDiesel > ƞDual > ƞOtto |
| C. | ƞDual> ƞDiesel > ƞOtto |
| D. | ƞDual> ƞOtto> ƞDiesel |
| Answer» B. ƞDiesel > ƞDual > ƞOtto | |
| 27. |
The air box/swept volume ratio should be in the range for single-cylinder engines |
| A. | 10- 100% |
| B. | 200-300% |
| C. | 500 600% |
| D. | > 1000% |
| Answer» D. > 1000% | |
| 28. |
Crankcase scavenged engines have delivery ratio of |
| A. | greater than 1 |
| B. | less than 1 |
| C. | equal to 1 |
| D. | none of the above |
| Answer» D. none of the above | |
| 29. |
The precess of breaking up or a liquid into fine droplets by spraying is called |
| A. | vaporisation |
| B. | carburetion |
| C. | ionisation |
| D. | atomisation. |
| Answer» E. | |
| 30. |
Main advantage of a two-stroke engine over four-stroke engine is |
| A. | more uniform torque on the crankshaft |
| B. | more power output for the cylinder of same dimensions |
| C. | absence of valves |
| D. | all of the above |
| Answer» E. | |
| 31. |
Knocking takes place in CI engines |
| A. | at the start of combustion |
| B. | at the end of combustion |
| C. | during combustion |
| D. | none of the above |
| Answer» B. at the end of combustion | |
| 32. |
Advantage of reciprocating IC engines over steam turbine is |
| A. | Mechanical simplicity |
| B. | Improved plant efficiency |
| C. | Lower average temperature |
| D. | all of the above |
| Answer» E. | |
| 33. |
Fuel consumption of diesel engines is not guaranteed at one quarter load because at suchlow 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 |
| Answer» D. the engine is rarely operated | |
| 34. |
Fuel is injected in a four-stroke CI engine |
| A. | at the end of suction stroke |
| B. | at the end of expansion stroke |
| C. | at the end of compression stroke |
| D. | at the end of exhaust stroke |
| Answer» D. at the end of exhaust stroke | |
| 35. |
When the engines are built to withstand the sane thermal and mechanical stresses |
| A. | ƞDiesel > ƞDual > ƞOtto |
| B. | ƞDual> ƞDiesel > ƞOtto |
| C. | ƞOtto> ƞDual > ƞDiesel |
| D. | ƞOtto> ƞDiesel > ƞDual |
| Answer» B. ƞDual> ƞDiesel > ƞOtto | |
| 36. |
Which of the following is one of the major exhaust emissions from CI engines compared toSI engines? |
| A. | Oxides of nitrogen |
| B. | Particulates |
| C. | CO and CO2 |
| D. | Unburnt hydrocarbon |
| Answer» C. CO and CO2 | |
| 37. |
What does the blue smoke in diesel engine indicate? |
| A. | Unburnt oil |
| B. | HC |
| C. | NOx |
| D. | CO |
| Answer» B. HC | |
| 38. |
With EFI (ELECTRONIC FUEL INJECTION) of diesel engines |
| A. | sharp start and stop is not possible |
| B. | very high injection pressure can be obtained |
| C. | sudden cylinder cut-off is impossible |
| D. | diagnostic properties are poor |
| Answer» C. sudden cylinder cut-off is impossible | |
| 39. |
For engine operating with rich mixtures the optimum spark timing |
| A. | must be advanced |
| B. | must be retarded |
| C. | must be at TDC |
| D. | none of the above |
| Answer» B. must be retarded | |
| 40. |
The limits of air-fuel for SI engine are |
| A. | 8/1 to 18/1 |
| B. | 8/1 to 50/1 |
| C. | 25/1 to 50/1 |
| D. | 50/1 to 100/1 |
| Answer» B. 8/1 to 50/1 | |
| 41. |
The air fuel ratio required for the efficient operation of a three approximately |
| A. | 5:1 |
| B. | 10:1 |
| C. | 15:1 |
| D. | 20:1S |
| Answer» D. 20:1S | |
| 42. |
Engines used for ships are normally |
| A. | four-stroke Sl engines of very high power |
| B. | two-stroke CI engines of very high power |
| C. | four-stroke Cl engines of high speed |
| D. | two-stroke SI engines of high power |
| Answer» C. four-stroke Cl engines of high speed | |
| 43. |
The output of a diesel engine can be increased without increasing the engine revolution orsize in following way |
| A. | feeding more fuel |
| B. | increasing flywheel size |
| C. | heating incoming air |
| D. | supercharging. |
| Answer» E. | |
| 44. |
The spark timing and combustion rate should be such that |
| A. | peak pressure occurs at TDC |
| B. | one half of the total pressure occurs at TDC |
| C. | ignition delay is reduced |
| D. | none of the above |
| Answer» C. ignition delay is reduced | |
| 45. |
Thermal efficiency of CI engine is higher than that of SI engine due |
| A. | light weight |
| B. | higher compression ratio |
| C. | constant pressure heat addition |
| D. | none of the above |
| Answer» C. constant pressure heat addition | |
| 46. |
In carburetor, Choke is incorporated |
| A. | Before the venturi |
| B. | After the venturi |
| C. | In the venturi |
| D. | Any of the above |
| Answer» B. After the venturi | |
| 47. |
The advantage of Root's supercharger is |
| A. | big pressure |
| B. | minimum maintenance |
| C. | consumes less power |
| D. | occupies less space |
| Answer» C. consumes less power | |
| 48. |
Octane number of iso-octane is |
| A. | 0 |
| B. | 30 |
| C. | 60 |
| D. | 100 |
| Answer» E. | |
| 49. |
Dwell meter is used for |
| A. | setting spark plug gap |
| B. | contact breaker gap |
| C. | setting the ignition advance |
| D. | setting |
| Answer» C. setting the ignition advance | |
| 50. |
In case of engines backfiring, the PCV valve: |
| A. | Opens maximum |
| B. | Closes |
| C. | Disintegrates |
| D. | Sticks in the centre position |
| Answer» C. Disintegrates | |