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.
| 251. |
The volumetric efficiency of a well designed engine may be |
| A. | 0 to 40% |
| B. | 0 to 60% |
| C. | 0 to 70% |
| D. | 5 to 90% |
| Answer» E. | |
| 252. |
Antiknock for compression ignition engines is |
| A. | apthene |
| B. | etra ethyl lead |
| C. | myl nitrate |
| D. | exadecane |
| Answer» D. exadecane | |
| 253. |
Combustion in compression ignition engines is |
| A. | omogeneous |
| B. | eterogeneous |
| C. | oth (A) and (B) |
| D. | aminar |
| Answer» C. oth (A) and (B) | |
| 254. |
The combustion in compression ignition engines is |
| A. | omogeneous |
| B. | eterogeneous |
| C. | oth (A) and (B) |
| D. | one of these |
| Answer» C. oth (A) and (B) | |
| 255. |
The loud pulsating noise heard within the cylinder of an internal combustion engine is known as |
| A. | etonation |
| B. | urbulence |
| C. | re-ignition |
| D. | upercharging |
| Answer» B. urbulence | |
| 256. |
The mechanical efficiency (ηm) of the engine is given by |
| A. | m = B.P/I.P |
| B. | m = I.P/B.P |
| C. | m = (B.P × I.P)/100 |
| D. | one of these |
| Answer» B. m = I.P/B.P | |
| 257. |
The increase of cooling water temperature in petrol engine will _________ the knocking tendency. |
| A. | ot effect |
| B. | ecrease |
| C. | ncrease |
| D. | one of these |
| Answer» D. one of these | |
| 258. |
In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _________ the knocking tendency. |
| A. | ot effected |
| B. | ecrease |
| C. | ncrease |
| D. | one of these |
| Answer» D. one of these | |
| 259. |
In petrol engines, advancing of the spark timing will _________ the knocking tendency. |
| A. | ot effect |
| B. | ecrease |
| C. | ncrease |
| D. | one of these |
| Answer» D. one of these | |
| 260. |
For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of |
| A. | : 1 |
| B. | 2 : 1 |
| C. | 5 : 1 |
| D. | 8 : 1 |
| Answer» C. 5 : 1 | |
| 261. |
If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the |
| A. | xhaust will be smoky |
| B. | iston rings would stick into piston grooves |
| C. | ngine starts overheating |
| D. | cavenging occurs |
| Answer» E. | |
| 262. |
The thermal efficiency of a petrol engine is _________ as compared to diesel engine. |
| A. | ame |
| B. | ess |
| C. | ore |
| D. | one of these |
| Answer» C. ore | |
| 263. |
Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following |
| A. | iston ring and cylinder wear |
| B. | ormation of hard coating on piston skirts |
| C. | il sludge in the engine crank case |
| D. | etonation |
| Answer» E. | |
| 264. |
If V₁ is the jet velocity and V₀ is the vehicle velocity, then propulsive efficiency of a turbojet engine is |
| A. | ₁ / (V₀ + V₁) |
| B. | ₀ / (V₀ + V₁) |
| C. | V₀ / (V₀ + V₁) |
| D. | V₁ / (V₀ + V₁) |
| Answer» D. V₁ / (V₀ + V₁) | |
| 265. |
The reflectivity depends upon |
| A. | eometry of the reflector |
| B. | nergy of neutrons |
| C. | roperties of the reflector |
| D. | ll of these |
| Answer» E. | |
| 266. |
Which is more viscous lube oil? |
| A. | EA 30 |
| B. | AE 50 |
| C. | AE 70 |
| D. | AE 80 |
| Answer» E. | |
| 267. |
The knocking in diesel engines may be prevented by |
| A. | educing the delay period |
| B. | aising the compression ratio |
| C. | ncreasing the inlet pressure of air |
| D. | ll of these |
| Answer» E. | |
| 268. |
The knocking tendency in spark ignition engines may be decreased by |
| A. | ontrolling the air-fuel mixture |
| B. | ontrolling the ignition timing |
| C. | ontrolling the exhaust temperature |
| D. | educing the compression ratio |
| Answer» E. | |
| 269. |
The knocking in diesel engines may be prevented by~! |
| A. | Reducing the delay period |
| B. | Raising the compression ratio |
| C. | Increasing the inlet pressure of air |
| D. | All of these |
| Answer» E. | |
| 270. |
The knocking tendency in spark ignition engines may be decreased by~! |
| A. | Controlling the air-fuel mixture |
| B. | Controlling the ignition timing |
| C. | Controlling the exhaust temperature |
| D. | Reducing the compression ratio |
| Answer» E. | |
| 271. |
The specific fuel consumption per BH hour for a petrol engine is approximately%! |
| A. | 0.15 kg |
| B. | 0.2 kg |
| C. | 0.25 kg |
| D. | 0.3 kg |
| Answer» D. 0.3 kg | |
| 272. |
The output of a diesel engine can be increased without increasing the engine revolution or size in following way%! |
| A. | Feeding more fuel |
| B. | Heating incoming air |
| C. | Scavenging |
| D. | Supercharging |
| Answer» E. | |
| 273. |
A spark plug gap is kept from%! |
| A. | 0.3 to 0.7 mm |
| B. | 0.2 to 0.8 mm |
| C. | 0.4 to 0.9 mm |
| D. | 0.6 to 1.0 mm |
| Answer» B. 0.2 to 0.8 mm | |
| 274. |
In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then _________ is employed.%! |
| A. | Fuel pump |
| B. | Injector |
| C. | Carburettor |
| D. | None of these |
| Answer» D. None of these | |
| 275. |
The theoretically correct mixture of air and petrol is%! |
| A. | 10 : 1 |
| B. | 15 : 1 |
| C. | 20 : 1 |
| D. | 25 : 1 |
| Answer» C. 20 : 1 | |
| 276. |
The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be%! |
| A. | Higher |
| B. | Lower |
| C. | Remain unaffected |
| D. | None of the above |
| Answer» B. Lower | |
| 277. |
Fuel consumption of diesel 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 |
| Answer» D. The engine is rarely operated | |
| 278. |
The knocking in spark ignition engines can be reduced by%! |
| A. | Retarding the spark |
| B. | Increasing the engine speed |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» D. None of these | |
| 279. |
Number of working strokes per min. for a two stroke cycle engine is _________ the speed of the engine in r.p.m.%! |
| A. | Equal to |
| B. | One-half |
| C. | Twice |
| D. | Four-times |
| Answer» B. One-half | |
| 280. |
The turbine of the turboprop engine is __________ that of the turbojet engine.%! |
| A. | Same as |
| B. | Smaller than |
| C. | Bigger than |
| D. | None of these |
| Answer» D. None of these | |
| 281. |
In loop scavenging, the top of the piston is%! |
| A. | Flat |
| B. | Contoured |
| C. | Slanted |
| D. | Depressed |
| Answer» C. Slanted | |
| 282. |
The air-fuel ratio in petrol engines is controlled by%! |
| A. | Controlling valve opening/closing |
| B. | Governing |
| C. | Injection |
| D. | Carburetion |
| Answer» E. | |
| 283. |
Which of the following statements is correct?%! |
| A. | All the irreversible engines have same efficiency |
| B. | All the reversible engines have same efficiency |
| C. | Both Rankine and Carnot cycles have same efficiency between same temperature limits |
| D. | All reversible engines working between same temperature limits have same efficiency |
| Answer» E. | |
| 284. |
Supercharging is the process of supplying the intake air to the engine cylinder at a density _________ the density of the surrounding atmosphere.%! |
| A. | Equal to |
| B. | Less than |
| C. | Greater than |
| D. | None of these |
| Answer» D. None of these | |
| 285. |
The reference fuels for knock rating of spark ignition engines would include%! |
| A. | Iso-octane and alpha-methyl naphthalene |
| B. | Normal octane and aniline |
| C. | Iso-octane and normal hexane |
| D. | Normal heptane and iso-octane |
| Answer» E. | |
| 286. |
The power actually developed by the engine cylinder of an I.C. engine is known as%! |
| A. | Theoretical power |
| B. | Actual power |
| C. | Indicated power |
| D. | None of these |
| Answer» D. None of these | |
| 287. |
Antiknock for compression ignition engines is%! |
| A. | Napthene |
| B. | Tetra ethyl lead |
| C. | Amyl nitrate |
| D. | Hexadecane |
| Answer» D. Hexadecane | |
| 288. |
The increase of cooling water temperature in petrol engine will _________ the knocking tendency.%! |
| A. | Not effect |
| B. | Decrease |
| C. | Increase |
| D. | None of these |
| Answer» D. None of these | |
| 289. |
The specific fuel consumption per B.P. hour for a petrol engine is about%! |
| A. | 0.2 kg |
| B. | 0.25 kg |
| C. | 0.3 kg |
| D. | 0.35 kg |
| Answer» C. 0.3 kg | |
| 290. |
In a cycle, the spark lasts roughly for%! |
| A. | 1 sec |
| B. | 0.1 sec |
| C. | 0.01 sec |
| D. | 0.001 sec |
| Answer» E. | |
| 291. |
*$_The inlet value of a four stroke cycle I.C engine remains open for nearly? |
| A. | 180° |
| B. | 125° |
| C. | 235° |
| D. | 200° |
| Answer» D. 200¬¨‚àû | |
| 292. |
*$_Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows? |
| A. | Using additives in the fuel |
| B. | Increasing the compression ratio |
| C. | Adherence to proper fuel specification |
| D. | Avoidance of overloading |
| Answer» C. Adherence to proper fuel specification | |
| 293. |
*$_The fuel valve in a four stroke cycle diesel engine? |
| A. | Opens at 15° after top dead center and closes at 20° before bottom dead center |
| B. | Opens at 15° before top dead center and closes at 20° after top dead center |
| C. | Opens at top dead center and closes at bottom dead center |
| D. | May open and close anywhere |
| Answer» C. Opens at top dead center and closes at bottom dead center | |
| 294. |
*$_Alpha-methyl-naphthalene (C‚ÇÅ‚ÇÅ H‚ÇÅ‚ÇÄ) has a cetane number of? |
| A. | 0 |
| B. | 50 |
| C. | 100 |
| D. | 120 |
| Answer» B. 50 | |
| 295. |
*/*_In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then _________ is employed.? |
| A. | Fuel pump |
| B. | Injector |
| C. | Carburettor |
| D. | None of these |
| Answer» D. None of these | |
| 296. |
*/*_The knocking in spark ignition engines can be reduced by? |
| A. | Retarding the spark |
| B. | Increasing the engine speed |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» D. None of these | |
| 297. |
*/*_Fuel consumption of diesel 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 |
| Answer» D. The engine is rarely operated | |
| 298. |
*/*_The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be? |
| A. | Higher |
| B. | Lower |
| C. | Remain unaffected |
| D. | None of the above |
| Answer» B. Lower | |
| 299. |
*/*_The theoretically correct mixture of air and petrol is? |
| A. | 10 : 1 |
| B. | 15 : 1 |
| C. | 20 : 1 |
| D. | 25 : 1 |
| Answer» C. 20 : 1 | |
| 300. |
*/*_The output of a diesel engine can be increased without increasing the engine revolution or size in following way? |
| A. | Feeding more fuel |
| B. | Heating incoming air |
| C. | Scavenging |
| D. | Supercharging |
| Answer» E. | |