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.
| 451. |
A 75 cc engine has following parameter as 75 cc$? |
| A. | Fuel tank capacity |
| B. | Lube oil capacity |
| C. | Swept volume |
| D. | Cylinder volume |
| Answer» D. Cylinder volume | |
| 452. |
High speed compression engines operate on$? |
| A. | Otto cycle |
| B. | Diesel cycle |
| C. | Dual combustion cycle |
| D. | All of these |
| Answer» D. All of these | |
| 453. |
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 |
| Answer» B. Compression starts at bottom dead center and ends at top dead center | |
| 454. |
For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of? |
| A. | 9 : 1 |
| B. | 12 : 1 |
| C. | 15 : 1 |
| D. | 18 : 1 |
| Answer» C. 15 : 1 | |
| 455. |
A carburettor is used to supply? |
| A. | Petrol, air and lubricating oil |
| B. | Air and diesel |
| C. | Petrol and lubricating oil |
| D. | Petrol and air |
| Answer» E. | |
| 456. |
For the same power developed in I.C. engines, the cheaper system is? |
| A. | Naturally aspirated |
| B. | Supercharged |
| C. | Centrifugal pump |
| D. | Turbo charger |
| Answer» C. Centrifugal pump | |
| 457. |
The reason for supercharging in any engine is to? |
| A. | Increase efficiency |
| B. | Increase power |
| C. | Reduce weight and bulk for a given output |
| D. | Effect fuel economy |
| Answer» D. Effect fuel economy | |
| 458. |
A 75 cc engine has following parameter as 75 cc? |
| A. | Fuel tank capacity |
| B. | Lube oil capacity |
| C. | Swept volume |
| D. | Cylinder volume |
| Answer» D. Cylinder volume | |
| 459. |
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 | |
| 460. |
During idling, a petrol engine requires _________ mixture.? |
| A. | Lean |
| B. | Rich |
| C. | Chemically correct |
| D. | None of these |
| Answer» C. Chemically correct | |
| 461. |
Scavenging is usually done to increase |
| A. | Thermal efficiency |
| B. | Speed |
| C. | Power output |
| D. | Fuel consumption |
| Answer» D. Fuel consumption | |
| 462. |
The maximum propulsive efficiency of a turbojet engine is at a speed of |
| A. | 1000 km/h |
| B. | 2000 km/h |
| C. | 2400 km/h |
| D. | 3000 km/h |
| Answer» D. 3000 km/h | |
| 463. |
The _________ engines can work on very lean mixture of fuel. |
| A. | Spark ignition |
| B. | Compression ignition |
| C. | Both (A) and (B) |
| D. | None of these |
| Answer» C. Both (A) and (B) | |
| 464. |
The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency. |
| A. | Increase |
| B. | Reduce |
| C. | Not effect |
| D. | None of these |
| Answer» C. Not effect | |
| 465. |
In a four stroke cycle petrol engine, the expansion |
| A. | Starts at top dead center and ends at bottom dead center |
| B. | Starts at 30° before top dead center and ends at 50° before bottom dead center |
| C. | Starts at 30° after top dead center and ends at 50° after bottom dead center |
| D. | May start and end anywhere |
| Answer» C. Starts at 30¬¨‚àû after top dead center and ends at 50¬¨‚àû after bottom dead center | |
| 466. |
Which of the following statement is correct regarding normal cetane? |
| A. | It is a standard fuel used for knock rating of diesel engines |
| B. | Its chemical name is normal hexadecane |
| C. | It has long carbon chain structure |
| D. | All of the above |
| Answer» E. | |
| 467. |
The octane number of petrol, generally available, is |
| A. | 20 to 40 |
| B. | 40 to 60 |
| C. | 60 to 80 |
| D. | 80 to 100 |
| Answer» E. | |
| 468. |
A supercharged engine as compared to an ordinary engine |
| A. | Requires smaller foundation |
| B. | Is lighter |
| C. | Consumes less lubricating oil |
| D. | All of these |
| Answer» E. | |
| 469. |
The increase of efficiency of a compression ignition engine, as the load decreases, is due to |
| A. | Higher maximum temperature |
| B. | Qualitative governing |
| C. | Quantitative governing |
| D. | Hit and miss governing |
| Answer» C. Quantitative governing | |
| 470. |
If the intake air temperature of I.C. engine increases, its efficiency will |
| A. | Increase |
| B. | Decrease |
| C. | Remain same |
| D. | None of these |
| Answer» C. Remain same | |
| 471. |
The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft |
| A. | 1/2 |
| B. | 1 |
| C. | 2 |
| D. | 4 |
| Answer» D. 4 | |
| 472. |
The working pressure and temperature inside the cylinder of an internal combustion engine is _________ as compared to a steam engine. |
| A. | Low |
| B. | Very low |
| C. | High |
| D. | Very high |
| Answer» E. | |
| 473. |
In the opposed piston diesel engine, the combustion chamber is located |
| A. | Above the piston |
| B. | Below the piston |
| C. | Between the pistons |
| D. | There is no such criterion |
| Answer» D. There is no such criterion | |
| 474. |
A diesel engine has |
| A. | 1 valve |
| B. | 2 valves |
| C. | 3 valves |
| D. | 4 valves |
| Answer» D. 4 valves | |
| 475. |
The brake power is the power available |
| A. | In the engine cylinder |
| B. | At the crank shaft |
| C. | At the crank pin |
| D. | None of these |
| Answer» C. At the crank pin | |
| 476. |
The fuel in diesel engine is normally injected at pressure of |
| A. | 5-10 kg/cm² |
| B. | 20-25 kg/cm² |
| C. | 60-80 kg/cm² |
| D. | 90-130 kg/cm² |
| Answer» E. | |
| 477. |
Which of the following fuel detonates readily? |
| A. | Benzene |
| B. | Iso-octane |
| C. | Normal heptane |
| D. | Alcohol |
| Answer» D. Alcohol | |
| 478. |
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in meters, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in meters, and d = Dia. of rope in meters) |
| A. | B.P = (Wl × 2πN)/60 watts |
| B. | B.P = [(W - S) πDN]/60 watts |
| C. | B.P = [(W - S) π (D + d) N]/60 watts |
| D. | All of these |
| Answer» E. | |
| 479. |
A higher compression ratio causes |
| A. | Pre-ignition |
| B. | Increase in detonation |
| C. | Acceleration in the rate of combustion |
| D. | Any one of these |
| Answer» E. | |
| 480. |
The accumulation of carbon in a cylinder results in increase of |
| A. | Clearance volume |
| B. | Volumetric efficiency |
| C. | Ignition time |
| D. | Effective compression ratio |
| Answer» E. | |
| 481. |
Engine pistons are usually made of aluminium alloy because it |
| A. | Is lighter |
| B. | Wear is less |
| C. | Absorbs shocks |
| D. | Is stronger |
| Answer» B. Wear is less | |
| 482. |
Diesel engine can work on very lean air fuel ratio of the order of 30: 1. A petrol engine can also work on such a lean ratio provided |
| A. | It is properly designed |
| B. | Best quality fuel is used |
| C. | Cannot work as it is impossible |
| D. | Flywheel size is proper |
| Answer» D. Flywheel size is proper | |
| 483. |
An hmh flame speed is obtained in diesel engine when air fuel ratio is |
| A. | Uniform throughout the mixture |
| B. | Chemically correct mixture |
| C. | About 35% of rich mixture |
| D. | About 10% of rich mixture |
| Answer» E. | |
| 484. |
The increase in intake temperature of internal combustion engines will _________ efficiency. |
| A. | Have no effect on |
| B. | Increase |
| C. | Decrease |
| D. | None of these |
| Answer» D. None of these | |
| 485. |
When crude oil is heated, then which of the following hydrocarbon is given off first? |
| A. | Kerosene |
| B. | Gasoline |
| C. | Paraffin |
| D. | Natural gas |
| Answer» E. | |
| 486. |
A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is |
| A. | 248 cm3 |
| B. | 252 cm3 |
| C. | 264 cm3 |
| D. | 286 cm3 |
| Answer» D. 286 cm3 | |
| 487. |
The scavenging efficiency of a four stroke cycle diesel engine is |
| A. | Below 50% |
| B. | Between 50 and 85% |
| C. | Between 85 and 95% |
| D. | Between 95 and 100% |
| Answer» E. | |
| 488. |
The thermodynamic cycle on which the petrol engine works, is |
| A. | Otto cycle |
| B. | Joule cycle |
| C. | Rankine cycle |
| D. | Stirling cycle |
| Answer» B. Joule cycle | |
| 489. |
The actual volume of fresh charge admitted in 4-stroke petrol engine is |
| A. | Equal to stroke volume |
| B. | Equal to stroke volume and clearance volume |
| C. | Less than stroke volume |
| D. | More than stroke volume |
| Answer» D. More than stroke volume | |
| 490. |
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 |
| Answer» C. Net calorific value of oil | |
| 491. |
Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged? |
| A. | Yes |
| B. | No |
| C. | To some extent |
| D. | Unpredictable |
| Answer» C. To some extent | |
| 492. |
The advancing of spark timing in spark ignition engines will _________ knocking tendency. |
| A. | Increase |
| B. | Reduce |
| C. | Not effect |
| D. | None of these |
| Answer» B. Reduce | |
| 493. |
Air fuel ratio at which a petrol engine cannot work is |
| A. | 8 : 1 |
| B. | 10 : 1 |
| C. | 15 : 1 |
| D. | 20 : 1 and less |
| Answer» E. | |
| 494. |
A diesel engine is _________ as compared to petrol engine, both running at rated load. |
| A. | Equally efficient |
| B. | Less efficient |
| C. | More efficient |
| D. | None of these |
| Answer» D. None of these | |
| 495. |
In a typical medium speed 4-stroke cycle diesel engines |
| A. | Exhaust valve opens at 35° before bottom 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 |
| Answer» B. Exhaust valve opens at bottom dead center and closes at top dead center | |
| 496. |
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 |
| Answer» E. | |
| 497. |
Which of the following is not an intern’s combustion engine?# |
| A. | 2-stroke petrol engine |
| B. | 4-stroke petrol engine |
| C. | Diesel engine |
| D. | Steam turbine |
| Answer» E. | |
| 498. |
The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the |
| A. | Jet area is automatically varied depending on the suction |
| B. | The flow from the main jet is diverted to the compensating jet with increase in speed |
| C. | The diameter of the jet is constant and the discharge coefficient is invariant |
| D. | Flow is produced due to the static head in the float chamber |
| Answer» E. | |
| 499. |
Flash point of fuel oil is |
| 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. | Temperature at which it catches fire without external aid |
| D. | Indicated by 90% distillation temperature, i.e. when 90% of sample oil has distilled off |
| Answer» B. Temperature at which it solidifies or congeals | |
| 500. |
The specific fuel consumption per B.P. hour for a diesel engine is about |
| A. | 0.2 kg |
| B. | 0.25 kg |
| C. | 0.3 kg |
| D. | 0.35 kg |
| Answer» B. 0.25 kg | |