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MCQOPTIONS
This section includes 454 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 351. |
Out of the following, from where you will prefer to take intake for air compressor$? |
| A. | From an air conditioned room maintained at 20°C |
| B. | From outside atmosphere at 1°C |
| C. | From coal yard side |
| D. | From a side where cooling tower is located nearby |
| Answer» E. | |
| 352. |
In n‚ÇÅ and n‚ÇÇ are the indices of compression for the first and second stage of compression, then the ratio of work-done on the first and second stages (W‚ÇÅ/W‚ÇÇ) with perfect intercooling is given by$? |
| A. | W‚ÇÅ/W‚ÇÇ = n‚ÇÇ(n‚ÇÅ - 1)/n‚ÇÅ(n‚ÇÇ - 1) |
| B. | W‚ÇÅ/W‚ÇÇ = n‚ÇÅ(n‚ÇÇ - 1)/n‚ÇÇ(n‚ÇÅ - 1) |
| C. | W‚ÇÅ/W‚ÇÇ = n‚ÇÅ/n‚ÇÇ |
| D. | W‚ÇÅ/W‚ÇÇ = n‚ÇÇ/n‚ÇÅ |
| Answer» C. W‚Äö√á√Ö/W‚Äö√á√á = n‚Äö√á√Ö/n‚Äö√á√á | |
| 353. |
The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the$? |
| A. | Rotor to static enthalpy rise in the stator |
| B. | Stator to static enthalpy rise in the rotor |
| C. | Rotor to static enthalpy rise in the stage |
| D. | Stator to static enthalpy rise in the stage |
| Answer» D. Stator to static enthalpy rise in the stage | |
| 354. |
Gas turbine as compared to steam turbine$? |
| A. | Requires less space for installation |
| B. | Has compressor and combustion chamber |
| C. | Has less efficiency |
| D. | All of these |
| Answer» E. | |
| 355. |
The efficiency of jet engine is$? |
| A. | Lower at low speed |
| B. | Higher at high altitudes |
| C. | Same at all altitudes |
| D. | Higher at high speed |
| Answer» C. Same at all altitudes | |
| 356. |
For perfect intercooling in a two stage compressor$? |
| A. | p‚ÇÇ/p‚ÇÅ = p‚ÇÉ/p‚ÇÇ |
| B. | p‚ÇÅ/p‚ÇÉ = p‚ÇÇ/p‚ÇÅ |
| C. | p‚ÇÅ = p3 |
| D. | p‚ÇÅ = p‚ÇÇ p3 |
| Answer» B. p‚Äö√á√Ö/p‚Äö√á√â = p‚Äö√á√á/p‚Äö√á√Ö | |
| 357. |
There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would$? |
| A. | Remain same |
| B. | Decrease |
| C. | Increase |
| D. | None of the above |
| Answer» D. None of the above | |
| 358. |
In axial flow compressor, exit flow angle deviation from the blade angle is a function of$? |
| A. | Blade camber |
| B. | Blade camber and incidence angle |
| C. | Space-chord ratio |
| D. | Blade camber and space-chord ratio |
| Answer» C. Space-chord ratio | |
| 359. |
An air compressor may be controlled by$? |
| A. | Throttle control |
| B. | Clearance control |
| C. | Blow off control |
| D. | Any one of the above |
| Answer» E. | |
| 360. |
Compression efficiency is compared against$? |
| A. | Ideal compression |
| B. | Adiabatic compression |
| C. | Isentropic compression |
| D. | Isothermal compression |
| Answer» E. | |
| 361. |
The ratio of isentropic work to Euler’s work is known as$? |
| A. | Compressor efficiency |
| B. | Isentropic efficiency |
| C. | Euler |
| D. | Pressure coefficient |
| Answer» E. | |
| 362. |
The thermal efficiency of a gas turbine as compared to a diesel plant is$? |
| A. | Same |
| B. | More |
| C. | Less |
| D. | Depends on other factors |
| Answer» D. Depends on other factors | |
| 363. |
The maximum delivery pressure in a rotary air compressor is$? |
| A. | 10 bar |
| B. | 20 bar |
| C. | 30 bar |
| D. | 50 bar |
| Answer» B. 20 bar | |
| 364. |
Standard air is the air at$? |
| A. | Atmospheric conditions at any specific location |
| B. | 20°C and 1 kg/cm² and relative humidity 36% |
| C. | 0°C and standard atmospheric conditions |
| D. | 15°C and 1 kg/cm² |
| Answer» C. 0¬¨‚àûC and standard atmospheric conditions | |
| 365. |
A turboprop is preferred to turbojet because$? |
| A. | It has high propulsive efficiency at high speeds |
| B. | It can fly at supersonic speeds |
| C. | It can fly at high elevations |
| D. | It has high power for take off |
| Answer» E. | |
| 366. |
The indicated work per unit mass of air delivered is$? |
| A. | Directly proportional to clearance volume |
| B. | Greatly affected by clearance volume |
| C. | Not affected by clearance volume |
| D. | Inversely proportional to clearance volume |
| Answer» D. Inversely proportional to clearance volume | |
| 367. |
An ideal air compressor cycle with clearance on P-V diagram can be represented by following processes$? |
| A. | One adiabatic, two isobaric, and one constant volume |
| B. | Two adiabatic and two isobaric |
| C. | Two adiabatic, one isobaric and one constant volume |
| D. | One adiabatic, one isobaric and two constant volumes |
| Answer» C. Two adiabatic, one isobaric and one constant volume | |
| 368. |
Standard air is the air at? |
| A. | Atmospheric conditions at any specific location |
| B. | 20°C and 1 kg/cm² and relative humidity 36% |
| C. | 0°C and standard atmospheric conditions |
| D. | 15°C and 1 kg/cm² |
| Answer» C. 0¬¨‚àûC and standard atmospheric conditions | |
| 369. |
The maximum delivery pressure in a rotary air compressor is? |
| A. | 10 bar |
| B. | 20 bar |
| C. | 30 bar |
| D. | 50 bar |
| Answer» B. 20 bar | |
| 370. |
The thermal efficiency of a gas turbine as compared to a diesel plant is? |
| A. | Same |
| B. | More |
| C. | Less |
| D. | Depends on other factors |
| Answer» D. Depends on other factors | |
| 371. |
In axial flow compressor, exit flow angle deviation from the blade angle is a function of? |
| A. | Blade camber |
| B. | Blade camber and incidence angle |
| C. | Space-chord ratio |
| D. | Blade camber and space-chord ratio |
| Answer» C. Space-chord ratio | |
| 372. |
The efficiency of jet engine is? |
| A. | Lower at low speed |
| B. | Higher at high altitudes |
| C. | Same at all altitudes |
| D. | Higher at high speed |
| Answer» C. Same at all altitudes | |
| 373. |
Compression efficiency is compared against? |
| A. | Ideal compression |
| B. | Adiabatic compression |
| C. | Isentropic compression |
| D. | Isothermal compression |
| Answer» E. | |
| 374. |
There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would? |
| A. | Remain same |
| B. | Decrease |
| C. | Increase |
| D. | None of the above |
| Answer» D. None of the above | |
| 375. |
For perfect intercooling in a two stage compressor? |
| A. | p‚ÇÇ/p‚ÇÅ = p‚ÇÉ/p‚ÇÇ |
| B. | p‚ÇÅ/p‚ÇÉ = p‚ÇÇ/p‚ÇÅ |
| C. | p‚ÇÅ = p3 |
| D. | p‚ÇÅ = p‚ÇÇ p3 |
| Answer» B. p‚Äö√á√Ö/p‚Äö√á√â = p‚Äö√á√á/p‚Äö√á√Ö | |
| 376. |
Gas turbine as compared to steam turbine? |
| A. | Requires less space for installation |
| B. | Has compressor and combustion chamber |
| C. | Has less efficiency |
| D. | All of these |
| Answer» E. | |
| 377. |
The indicated work per unit mass of air delivered is? |
| A. | Directly proportional to clearance volume |
| B. | Greatly affected by clearance volume |
| C. | Not affected by clearance volume |
| D. | Inversely proportional to clearance volume |
| Answer» D. Inversely proportional to clearance volume | |
| 378. |
An air compressor may be controlled by? |
| A. | Throttle control |
| B. | Clearance control |
| C. | Blow off control |
| D. | Any one of the above |
| Answer» E. | |
| 379. |
Ram compression in turbojet involves? |
| A. | Reduction of speed of incoming air and conversion of part of it into pressure energy |
| B. | Compression of inlet air |
| C. | Increasing speed of incoming air |
| D. | Lost work |
| Answer» B. Compression of inlet air | |
| 380. |
Which is false statement about multistage compression?? |
| A. | Power consumption per unit of air delivered is low |
| B. | Volumetric efficiency is high |
| C. | It is best suited for compression ratios around 7:1 |
| D. | The moisture in air is condensed in the inter-cooler |
| Answer» C. It is best suited for compression ratios around 7:1 | |
| 381. |
A rocket engine uses __________ for the combustion of its fuel.? |
| A. | Surrounding air |
| B. | Compressed atmospheric air |
| C. | Its own oxygen |
| D. | None of these |
| Answer» D. None of these | |
| 382. |
A closed gas turbine in which fuel is burnt directly in the air is not possible because of? |
| A. | Paucity of O2 |
| B. | Increasing gas temperature |
| C. | High specific volume |
| D. | High friction losses |
| Answer» B. Increasing gas temperature | |
| 383. |
A rocket engine for the combustion of its fuel? |
| A. | Carries its own oxygen |
| B. | Uses surrounding air |
| C. | Uses compressed atmospheric air |
| D. | Does not require oxygen |
| Answer» B. Uses surrounding air | |
| 384. |
A turboprop is preferred to turbojet because? |
| A. | It has high propulsive efficiency at high speeds |
| B. | It can fly at supersonic speeds |
| C. | It can fly at high elevations |
| D. | It has high power for take off |
| Answer» E. | |
| 385. |
The ratio of isentropic work to Euler’s work is known as? |
| A. | Compressor efficiency |
| B. | Isentropic efficiency |
| C. | Euler |
| D. | Pressure coefficient |
| Answer» E. | |
| 386. |
A rocket works with maximum overall efficiency when air craft velocity is equal to the? |
| A. | Jet velocity |
| B. | Twice the jet velocity |
| C. | Half the jet velocity |
| D. | Average of the jet velocity |
| Answer» D. Average of the jet velocity | |
| 387. |
Which is false statement about air receivers?? |
| A. | These are used to dampen pulsations |
| B. | These act as reservoir to take care of sudden demands |
| C. | These increase compressor efficiency |
| D. | These knock out some oil and moisture |
| Answer» D. These knock out some oil and moisture | |
| 388. |
Gas turbines for power generation are normally used |
| A. | To supply base load requirements |
| B. | To supply peak load requirements |
| C. | To enable start thermal power plant |
| D. | In emergency |
| Answer» C. To enable start thermal power plant | |
| 389. |
The hottest point in a gas turbine is |
| A. | at the base |
| B. | at the tip |
| C. | in the center |
| D. | between ~ to i of the blade height |
| Answer» E. | |
| 390. |
If infinite number of heaters be used in a gas turbine, then expansion process in turbine approaches |
| A. | Isothermal |
| B. | Isentropic |
| C. | Adiabatic |
| D. | Isochoric |
| Answer» B. Isentropic | |
| 391. |
The efficiency of the vane blower is (where W‚ÇÅ = Workdone due to compression, and W‚ÇÇ = Workdone due to back flow)$ |
| A. | W‚ÇÅ/(W‚ÇÅ + W‚ÇÇ) |
| B. | W‚ÇÇ/(W‚ÇÅ + W‚ÇÇ) |
| C. | (W‚ÇÅ + W‚ÇÇ)/W‚ÇÅ |
| D. | (W‚ÇÅ + W‚ÇÇ)/W‚ÇÇ |
| Answer» C. (W‚Äö√á√Ö + W‚Äö√á√á)/W‚Äö√á√Ö | |
| 392. |
The overall isothermal efficiency of the compressor is defined as the ratio of |
| A. | Work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio |
| B. | Isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor |
| C. | Volume of free air delivery per stroke to the swept volume of the piston |
| D. | Isentropic power to the power required to drive the compressor |
| Answer» C. Volume of free air delivery per stroke to the swept volume of the piston | |
| 393. |
The working fluid in a turbine is |
| A. | In two phases |
| B. | In three phases |
| C. | In a single phase |
| D. | In the form of air and water mixture |
| Answer» D. In the form of air and water mixture | |
| 394. |
When the temperature of air leaving the inter-cooler, in a two stage compression with inter-cooler, is ________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling. |
| A. | Equal to |
| B. | Less than |
| C. | More than |
| D. | None of these |
| Answer» B. Less than | |
| 395. |
The air entry velocity m a rocket as compared to aircraft is |
| A. | Same |
| B. | More |
| C. | Less |
| D. | Zero |
| Answer» E. | |
| 396. |
The degree of reaction is usually kept ________ for all types of axial flow compressors. |
| A. | 0.2 |
| B. | 0.3 |
| C. | 0.4 |
| D. | 0.5 |
| Answer» E. | |
| 397. |
Work ratio of a gas turbine may be improved by |
| A. | Decreasing the compression work |
| B. | Increasing the compression work |
| C. | Increasing the turbine work |
| D. | Both (A) and (C) above |
| Answer» E. | |
| 398. |
In air breathing jet engine, the jet is formed by expanding |
| A. | Highly heated atmospheric air |
| B. | Solids |
| C. | Liquid |
| D. | Plasma |
| Answer» B. Solids | |
| 399. |
Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on |
| A. | Mass flow rate |
| B. | Pressure ratio |
| C. | Change in load |
| D. | Stagnation pressure at the outlet |
| Answer» E. | |
| 400. |
The ratio of work done per cycle to the swept volume in case of compressor is called |
| A. | Compression index |
| B. | Compression ratio |
| C. | Compressor efficiency |
| D. | Mean effective pressure |
| Answer» E. | |