MCQOPTIONS
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MCQOPTIONS
This section includes 39 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. |
In a diesel engine___(a) fuel injection pump is used(b) fuel injection and carburetor is used(c) fuel injector is used(d) neither fuel injection pump nor injector is used |
| A. | (a) alone is true |
| B. | (c) alone is true |
| C. | (a) and (c) both are true |
| D. | (a), (b), (c), (d), all are true |
| Answer» D. (a), (b), (c), (d), all are true | |
| 2. |
In a SI engine, combustion stage I takes 1 ms and combustion stage II takes 1.5 ms when the engine runs at 1000 rpm. If stage I time duration is independent of engine speed what will be the additional spark advance necessary when the engine speed is doubled? |
| A. | 0° |
| B. | 6° |
| C. | 12° |
| D. | 24° |
| Answer» C. 12° | |
| 3. |
Ignition accelerators are substances which |
| A. | increase the rate of pre-flame reaction and reduce the ignition lag |
| B. | increase knock |
| C. | reduce detonation |
| D. | increase thermal efficiency |
| Answer» B. increase knock | |
| 4. |
A dynamometer is used for measuring |
| A. | speed of a machine |
| B. | torque exerted by or on a machine |
| C. | kinetic energy of the system in which it is used |
| D. | none of the above |
| Answer» C. kinetic energy of the system in which it is used | |
| 5. |
A throttle governed steam engine develops 15 kW with 280 kg power of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW of power will be nearly |
| A. | 340 kg/hr |
| B. | 150 kg/hr |
| C. | cannot be calculated |
| D. | 280 kg/hr |
| Answer» B. 150 kg/hr | |
| 6. |
In a SI engine, advancing of spark timing will |
| A. | Increase knocking tendency |
| B. | Reduce knocking tendency |
| C. | Not have any effect on knocking |
| D. | Depend on intensity of spark only |
| Answer» B. Reduce knocking tendency | |
| 7. |
How self-ignition temperature of petrol be compared to that of diesel? |
| A. | Higher |
| B. | Lower |
| C. | Same |
| D. | Insufficient data |
| Answer» B. Lower | |
| 8. |
For the same compression ratio, the thermal efficiency of an Otto cycle: |
| A. | first decreases and then remains the same as that of a diesel cycle |
| B. | is less than that of a diesel cycle |
| C. | is greater than that of a diesel cycle |
| D. | is the same as that of a diesel cycle |
| Answer» D. is the same as that of a diesel cycle | |
| 9. |
If ip → indicated power, bp → brake power, fp → frictional power. Which of the following statement is true for IC engine: |
| A. | ip > bp |
| B. | ip < bp |
| C. | ip < fp |
| D. | fp = ip + bp |
| Answer» B. ip < bp | |
| 10. |
A certain engine produces 10 kW indicated power. Its mechanical efficiency is 70%. Then the frictional power is |
| A. | 2 kW |
| B. | 2.5 kW |
| C. | 3 kW |
| D. | 3.5 kW |
| Answer» D. 3.5 kW | |
| 11. |
Mechanical efficiency of an automobile engine usually varies in the range |
| A. | 50 - 60 % |
| B. | 60 - 70 % |
| C. | 70 - 90 % |
| D. | more than 90% |
| Answer» D. more than 90% | |
| 12. |
For the same compression ratio and heat rejection |
| A. | ηOtto > ηDual > ηDiesel |
| B. | ηDiesel > ηDual > ηOtto |
| C. | ηDual > ηDiesel > ηOtto |
| D. | ηDual > ηOtto > ηDiesel |
| Answer» B. ηDiesel > ηDual > ηOtto | |
| 13. |
Gudgeon pin forms the link between |
| A. | Piston and big end of connecting rod |
| B. | Piston and small end of connecting rod |
| C. | Connecting rod and crank |
| D. | Big end and small end |
| Answer» C. Connecting rod and crank | |
| 14. |
Diagram factor is defined as the ratio of |
| A. | theoretical m.e.p. and actual m.e.p. |
| B. | actual m.e.p. and theoretical m.e.p. |
| C. | theoretical m.e.p. and swept volume |
| D. | actual m.e.p. and swept volume |
| Answer» C. theoretical m.e.p. and swept volume | |
| 15. |
Mechanical efficiency is the ratio of |
| A. | Brake power to heat input |
| B. | Indicated power to heat input |
| C. | Brake power to indicated power |
| D. | Friction loss to heat input |
| Answer» D. Friction loss to heat input | |
| 16. |
For petrol engine, the method of governing employed is |
| A. | Quantity governing |
| B. | Quality governing |
| C. | Hit and miss governing |
| D. | None of the above |
| Answer» B. Quality governing | |
| 17. |
Consider the following statements regarding supercharging of CI engines:1. Supercharging results in a quieter and smoother operation of a CI engine2. Supercharging of a CI engine requires an increase in valve overlap3. The limit of supercharging for a CI engine is reached by thermal and mechanical loadingWhich of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» B. 1 and 2 only | |
| 18. |
An IC engine produces an indicated power of 12 kW. If the mechanical efficiency of the engine is 90%, then loss of power due to friction is given as: |
| A. | 1.2 kW |
| B. | 2.2 kW |
| C. | 3.2 kW |
| D. | 0.2 kW |
| Answer» B. 2.2 kW | |
| 19. |
In a CI engine, squish is created |
| A. | towards the end of compression stroke |
| B. | at the end of suction stroke |
| C. | at the beginning of suction stroke |
| D. | during the combustion |
| Answer» B. at the end of suction stroke | |
| 20. |
In a 1000 cc four-stroke IC engine with crank running at 1000 rpm, if the mean effective pressure is 400 kPa and efficiency of engine is 0.5, then brake power of the engine is |
| A. | 5/3 kW |
| B. | 4/7 kW |
| C. | 3/5 kW |
| D. | 7/9 kW |
| Answer» B. 4/7 kW | |
| 21. |
If stroke volume of engine = 300 cc, clearance volume of engine = 20 cc. The compression ratio of engine will be: |
| A. | 15 |
| B. | 16 |
| C. | 14 |
| D. | 17 |
| Answer» C. 14 | |
| 22. |
In a three-way catalytic converter, the first converter controls : |
| A. | HC |
| B. | CO |
| C. | NO |
| D. | All the above |
| Answer» D. All the above | |
| 23. |
An engine working on Otto cycle consumes 8 litres of fuel per hour and develops 25 kW. The specific gravity of fuel is 0.75 and its calorific value is 44000 kJ/kg. The indicated thermal efficiency of the engine is: |
| A. | 54.5% |
| B. | 24.2% |
| C. | 34.1% |
| D. | 28.4% |
| Answer» D. 28.4% | |
| 24. |
A 4-stroke, 6-cylinder gas engine with a stroke volume of 1.75 litres develops 26.25 kW at 506 r.p.m and the MEP is 600 kN/m2. The number of misfires per minute per cylinder will be |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» B. 4 | |
| 25. |
In a four-stroke engine, the working cycle is completed in- |
| A. | One revolution of the crankshaft |
| B. | Two revolutions of the crankshaft |
| C. | Four revolutions of the crankshaft |
| D. | Three revolutions of the crankshaft |
| Answer» C. Four revolutions of the crankshaft | |
| 26. |
Mean effective pressure at a given compression ratio is maximum when the fuel-air ratio is |
| A. | Higher than stoichiometric |
| B. | Lower than stoichiometric |
| C. | Equal to stoichiometric |
| D. | None of the above |
| Answer» B. Lower than stoichiometric | |
| 27. |
A two-stroke cycle engine ____ as compared to a four-stroke cycle engine of the same size. |
| A. | has greater thermal efficiency |
| B. | has greater volumetric efficiency |
| C. | produces more power |
| D. | has less wear and tear of moving parts |
| Answer» D. has less wear and tear of moving parts | |
| 28. |
Morse test is applicable only to |
| A. | Single cylinder SI engines |
| B. | Single cylinder CI engines |
| C. | Multi-cylinder CI engines |
| D. | Multi-cylinder SI and CI engines |
| Answer» E. | |
| 29. |
A single-cylinder, single-acting compressor has a bore D, stroke L, radius of the cylinder R and rotational speed n revolutions per second. The piston displacement of the compressor is given by: |
| A. | (πD2Ln)/4 |
| B. | (πR2Ln)/2 |
| C. | (πD2Ln)/2 |
| D. | (πR2Ln)/4 |
| Answer» B. (πR2Ln)/2 | |
| 30. |
A four stroke, four-cylinder SI engine has a swept volume of 450 cc and compression ratio is 8. The clearance volume of each cylinder is equal to |
| A. | 48 cc |
| B. | 55 cc |
| C. | 65 cc |
| D. | 70 cc |
| Answer» D. 70 cc | |
| 31. |
Brake thermal efficiency of SI engine is in the range of |
| A. | 35% to 60% |
| B. | 25% to 35% |
| C. | 60% to 80% |
| D. | None of the above |
| Answer» C. 60% to 80% | |
| 32. |
In four stroke engines, the camshaft gear has: |
| A. | Half the teeth as on crankshaft gear |
| B. | Equal number of teeth as on crank shaft gear |
| C. | Twice the number of teeth as on crank shaft gear |
| D. | Four times the number of teeth as on crank shaft gear |
| Answer» D. Four times the number of teeth as on crank shaft gear | |
| 33. |
A 4 - cylinder, 4 - stroke single acting petrol engine consumes 6 kg of fuel per minute at 800 rpm when the air - fuel ratio of the mixture supplied is 9 : 1. The temperature is 650 K and pressure is 12.5 bar at the end of compression stroke. Take R = 300 Nm/kg.K, diameter of cylinder as 8 cm, stroke of cylinder as 10 cm. The compression ratio will be nearly |
| A. | 6.2 |
| B. | 5.7 |
| C. | 5.2 |
| D. | 4.6 |
| Answer» B. 5.7 | |
| 34. |
A distributor in a spark ignition engines performs the function of: |
| A. | Distributing the right quantity of fuel oil to the desired cylinder |
| B. | Distributing the air requirement appropriately |
| C. | Distributing the power to the wheels |
| D. | Providing the correct firing order in the engine |
| Answer» E. | |
| 35. |
A dynamometer is an equipment used to measure |
| A. | current and voltage of generator |
| B. | dynamic loads over cyclic times |
| C. | fatigue propagation due to dynamic loads |
| D. | torque and power of an engine |
| Answer» E. | |
| 36. |
For a single-cylinder four-stroke oil engine, indicated power is 15 kW, the calorific value of fuel is 40000 kJ/kg and fuel consumed is 0.001 kg/s. What will be the indicated thermal efficiency? |
| A. | 40% |
| B. | 37.5% |
| C. | 62.5% |
| D. | 75% |
| Answer» C. 62.5% | |
| 37. |
Clearance ratio is: |
| A. | swept volume / clearance volume |
| B. | clearance volume / swept volume |
| C. | total volume / swept volume |
| D. | clearance volume / total volume |
| Answer» C. total volume / swept volume | |
| 38. |
An engine at full load delivers 200 kW brake power. It requires 25 kW to rotate it without fuel at the same speed. The mechanical efficiency at half load is: |
| A. | 80 % |
| B. | 50 % |
| C. | 25 % |
| D. | 66.7 % |
| Answer» B. 50 % | |
| 39. |
For the same rated power and same engine speed of a two stroke engine and a four stroke engine. Which of the following statement is correct |
| A. | Heavier flywheel is required for two stroke engine |
| B. | Heavier flywheel is required for four stroke engine |
| C. | Mass of the flywheel should be same for both the engines |
| D. | Mass of the flywheel depends upon the load on the engine |
| Answer» C. Mass of the flywheel should be same for both the engines | |