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.
| 401. |
__As compared to air standard cycle, in actual working, the effect of variation in specific heats is to__ |
| A. | Increase maximum pressure and maximum temperature |
| B. | Reduce maximum pressure and maximum temperature |
| C. | Increase maximum pressure and decrease maximum temperature |
| D. | Decrease maximum pressure and increase maximum temperature |
| Answer» C. Increase maximum pressure and decrease maximum temperature | |
| 402. |
_Morse test can be conducted for$? |
| A. | Petrol engines |
| B. | Diesel engines |
| C. | Multi cylinder engines |
| D. | All of these |
| Answer» D. All of these | |
| 403. |
_In order to eliminate knocking in compression ignition engines, there should be$? |
| A. | Short delay period |
| B. | Late auto-ignition |
| C. | Low compression ratio |
| D. | High self ignition temperature of fuel |
| Answer» B. Late auto-ignition | |
| 404. |
_The magneto in an automobile is basically$? |
| A. | Transformer |
| B. | D.C. generator |
| C. | Capacitor |
| D. | Magnetic circuit |
| Answer» C. Capacitor | |
| 405. |
_Diesel fuel, compared to petrol is$? |
| A. | Less difficult to ignite |
| B. | Just about the same difficult to ignite |
| C. | More difficult to ignite |
| D. | Highly ignitable |
| Answer» D. Highly ignitable | |
| 406. |
_The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed$? |
| A. | 80°C |
| B. | 120°C |
| C. | 180°C |
| D. | 240°C |
| Answer» D. 240¬¨‚àûC | |
| 407. |
_The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at$? |
| A. | 1500 rpm |
| B. | 750 rpm |
| C. | 3000 rpm |
| D. | Any value independent of engine speed |
| Answer» C. 3000 rpm | |
| 408. |
_Which of the following does not relate to a compression ignition engine?$? |
| A. | Fuel pump |
| B. | Fuel injector |
| C. | Governor |
| D. | Carburettor |
| Answer» E. | |
| 409. |
_The pressure at the end of compression, in petrol engines, is approximately$? |
| A. | 10 bar |
| B. | 20 bar |
| C. | 25 bar |
| D. | 35 bar |
| Answer» B. 20 bar | |
| 410. |
_Which of the following medium is compressed in a Diesel engine cylinder?$? |
| A. | Air alone |
| B. | Air and fuel |
| C. | Air and lub oil |
| D. | Fuel alone |
| Answer» B. Air and fuel | |
| 411. |
_The thermal efficiency of diesel engines is about$? |
| A. | 15% |
| B. | 30% |
| C. | 50% |
| D. | 70% |
| Answer» E. | |
| 412. |
_In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have$? |
| A. | Low density |
| B. | Low temperature |
| C. | Long ignition delay |
| D. | All of these |
| Answer» E. | |
| 413. |
_In compression ignition engines, swirl denotes a$? |
| A. | Haphazard motion of the gases in the chamber |
| B. | Rotary motion of the gases in the chamber |
| C. | Radial motion of the gases in the chamber |
| D. | None of the above |
| Answer» C. Radial motion of the gases in the chamber | |
| 414. |
_The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of$? |
| A. | Morse test |
| B. | Prony brake test |
| C. | Motoring test |
| D. | Heat balance test |
| Answer» B. Prony brake test | |
| 415. |
_Iso-octane (C‚Çà H‚ÇÅ‚Çà ) has octane number of$? |
| A. | 0 |
| B. | 50 |
| C. | 100 |
| D. | 120 |
| Answer» D. 120 | |
| 416. |
_The combustion in compression ignition engines is$? |
| A. | Homogeneous |
| B. | Heterogeneous |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» C. Both (A) and (B) | |
| 417. |
_In petrol engines, advancing of the spark timing will _________ the knocking tendency.$? |
| A. | Not effect |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» D. None of these | |
| 418. |
_The volumetric efficiency of a well designed engine may be$? |
| A. | 30 to 40% |
| B. | 40 to 60% |
| C. | 60 to 70% |
| D. | 75 to 90% |
| Answer» E. | |
| 419. |
_The mechanical efficiency (ηm) of the engine is given by$? |
| A. | ηm = B.P/I.P |
| B. | ηm = I.P/B.P |
| C. | ηm = (B.P × I.P)/100 |
| D. | None of these |
| Answer» B. ≈í‚àëm = I.P/B.P | |
| 420. |
_The cetane number of diesel oil, generally available, is$? |
| A. | 20 to 25 |
| B. | 25 to 30 |
| C. | 30 to 40 |
| D. | 40 to 55 |
| Answer» E. | |
| 421. |
_In a petrol engine, if diesel is used, then the engine will$? |
| A. | Not run |
| B. | Run more efficiently |
| C. | Run at high speed |
| D. | Explode |
| Answer» B. Run more efficiently | |
| 422. |
_The minimum cranking speed in case of petrol engine is about$? |
| A. | Half the operating speed |
| B. | One fourth of operating speed |
| C. | 250 - 300 rpm |
| D. | 60 - 80 rpm |
| Answer» E. | |
| 423. |
_In a four stroke cycle petrol engine, the charge is ignited at$? |
| A. | 30° before top dead center |
| B. | 30° after top dead center |
| C. | 30° before bottom dead center |
| D. | 30° after bottom dead center |
| Answer» B. 30¬¨‚àû after top dead center | |
| 424. |
_If the temperature of intake air in internal combustion engine increases, then its efficiency will$? |
| A. | Remain same |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» C. Increase | |
| 425. |
_The following volume of air is required for consuming 1 liter of fuel by a four stroke engine$? |
| A. | 1 m3 |
| B. | 5 m3 |
| C. | 56 m3 |
| D. | 910 m3 |
| Answer» E. | |
| 426. |
_The process of breaking up or a liquid into fine droplets by spraying is called$? |
| A. | Vaporisation |
| B. | Carburetion |
| C. | Ionization |
| D. | Atomization |
| Answer» E. | |
| 427. |
_If V‚ÇÅ is the jet velocity and V‚ÇÄ is the vehicle velocity, then the propulsive efficiency of a rocket is given by$? |
| A. | [2(V₀/V₁)]/ [1 + (V₀/V₁)²] |
| B. | (V₀/V₁)/ [1 + (V₀/V₁)²] |
| C. | V‚ÇÄ/(V‚ÇÄ + V‚ÇÅ) |
| D. | V‚ÇÅ/(V‚ÇÄ + V‚ÇÅ) |
| Answer» B. (V‚Äö√á√Ñ/V‚Äö√á√Ö)/ [1 + (V‚Äö√á√Ñ/V‚Äö√á√Ö)¬¨‚â§] | |
| 428. |
_The ignition quality of diesel oil is expressed by$? |
| A. | Cetane number |
| B. | Octane number |
| C. | Calorific value |
| D. | None of these |
| Answer» B. Octane number | |
| 429. |
_The exhaust valve in a four stroke cycle petrol engine$? |
| A. | Opens at 50° before bottom dead center and closes at 15° after top dead center |
| B. | Opens at bottom dead center and closes at top dead center |
| C. | Opens at 50° after bottom dead center and closes at 15° before top dead center |
| D. | May open and close anywhere |
| Answer» B. Opens at bottom dead center and closes at top dead center | |
| 430. |
_Installation of supercharger on a four cycle diesel engine can result in the following percentage increase in power$? |
| A. | Up to 35% |
| B. | Up to 50% |
| C. | Up to 75% |
| D. | Up to 100% |
| Answer» E. | |
| 431. |
_A mixture containing 65% of iso-octane and 35% of normal heptane will have$? |
| A. | Cetane number 65 |
| B. | Octane number 65 |
| C. | Cetane number 35 |
| D. | Octane number 35 |
| Answer» C. Cetane number 35 | |
| 432. |
_Detonation is harmful due to$? |
| A. | Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine |
| B. | Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls |
| C. | High intensity of knock causes crankshaft vibration and the engine runs rough |
| D. | None of the above |
| Answer» E. | |
| 433. |
_Stoichiometric ratio is$? |
| A. | Chemically correct air-fuel ratio by weight |
| B. | Chemically correct air-fuel ratio by volume |
| C. | Actual air-fuel ratio for maximum efficiency |
| D. | None of the above |
| Answer» C. Actual air-fuel ratio for maximum efficiency | |
| 434. |
_An engine indicator is used to determine the following$? |
| A. | Speed |
| B. | Temperature |
| C. | Volume of cylinder |
| D. | m.e.p. and I.H.P. |
| Answer» E. | |
| 435. |
_The pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.$? |
| A. | Equal to |
| B. | Below |
| C. | Above |
| D. | None of these |
| Answer» D. None of these | |
| 436. |
_Which one of the following engines will have heavier flywheel than the remaining ones?$? |
| A. | 30 kW four-stroke petrol engine running at 1500 r.p.m. |
| B. | 30 kW two-stroke petrol engine running at 1500 r.p.m. |
| C. | 30 kW two-stroke diesel engine running at 750 r.p.m. |
| D. | 30 kW four-stroke diesel engine running at 750 r.p.m. |
| Answer» B. 30 kW two-stroke petrol engine running at 1500 r.p.m. | |
| 437. |
_The self ignition temperature of petrol is _________ as compared to diesel oil.$? |
| A. | Same |
| B. | Lower |
| C. | Higher |
| D. | None of these |
| Answer» D. None of these | |
| 438. |
_The calorific value of gaseous fuels is expressed in terms of$? |
| A. | kcal |
| B. | kcal/kg |
| C. | kcal/m² |
| D. | kcal/m3 |
| Answer» E. | |
| 439. |
_Pour point of fuel oil is the$? |
| A. | Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame |
| B. | Temperature at which it solidifies or congeals |
| C. | It catches fire without external aid |
| D. | Indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off |
| Answer» C. It catches fire without external aid | |
| 440. |
_The ignition of the charge by some hot surface within the engine before the passage of spark is called$? |
| A. | Pre-ignition |
| B. | Detonation |
| C. | Ignition delay |
| D. | Auto-ignition |
| Answer» B. Detonation | |
| 441. |
_Which of the following statement is correct regarding petrol engines?$? |
| A. | A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure |
| B. | The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug |
| C. | The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition |
| D. | All of the above |
| Answer» C. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition | |
| 442. |
_Which is more viscous lube oil?$? |
| A. | SEA 30 |
| B. | SAE 50 |
| C. | SAE 70 |
| D. | SAE 80 |
| Answer» E. | |
| 443. |
_A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of$? |
| A. | 75% iso-octane and 25% normal heptane |
| B. | 75% normal heptane and 25% iso-octane |
| C. | 75% petrol and 25% diesel |
| D. | 75% diesel and 25% petrol |
| Answer» B. 75% normal heptane and 25% iso-octane | |
| 444. |
_In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.$? |
| A. | Equal to |
| B. | Below |
| C. | Above |
| D. | None of these |
| Answer» C. Above | |
| 445. |
_Gaseous fuel guarantees are based on$? |
| A. | Calorific value of oil |
| B. | Low heat value of oil |
| C. | High heat value of oil |
| D. | Mean heat value of oil |
| Answer» C. High heat value of oil | |
| 446. |
_A petrol engine, during suction stroke draws$? |
| A. | Air only |
| B. | Petrol only |
| C. | A mixture of petrol and air |
| D. | None of these |
| Answer» D. None of these | |
| 447. |
_If V‚ÇÅ is the jet velocity and V‚ÇÄ is the vehicle velocity, then propulsive efficiency of a turbojet engine is$? |
| A. | V‚ÇÅ / (V‚ÇÄ + V‚ÇÅ) |
| B. | V‚ÇÄ / (V‚ÇÄ + V‚ÇÅ) |
| C. | 2V‚ÇÄ / (V‚ÇÄ + V‚ÇÅ) |
| D. | 2V‚ÇÅ / (V‚ÇÄ + V‚ÇÅ) |
| Answer» D. 2V‚Äö√á√Ö / (V‚Äö√á√Ñ + V‚Äö√á√Ö) | |
| 448. |
In a four stroke cycle petrol engine, the inlet valve$? |
| A. | Opens at top dead center and closes at bottom dead center |
| B. | Opens at 20° before top dead center and closes at 40° after bottom dead center |
| C. | Opens at 20° after top dead center and closes at 20° before bottom dead center |
| D. | May open or close anywhere |
| Answer» C. Opens at 20¬¨‚àû after top dead center and closes at 20¬¨‚àû before bottom dead center | |
| 449. |
During idling, a petrol engine requires _________ mixture.$? |
| A. | Lean |
| B. | Rich |
| C. | Chemically correct |
| D. | None of these |
| Answer» C. Chemically correct | |
| 450. |
A stoichiometric air-fuel ratio is$? |
| A. | Chemically correct mixture |
| B. | Lean mixture |
| C. | Rich mixture for idling |
| D. | Rich mixture for over loads |
| Answer» B. Lean mixture | |