MCQOPTIONS
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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.
| 1. |
The ratio of the net work obtained from the gas turbine plant to the turbine work is known as |
| A. | ompression ratio |
| B. | ork ratio |
| C. | ressure ratio |
| D. | one of these |
| Answer» C. ressure ratio | |
| 2. |
A turboprop is preferred to turbojet because |
| A. | t has high propulsive efficiency at high speeds |
| B. | t can fly at supersonic speeds |
| C. | t can fly at high elevations |
| D. | t has high power for take off |
| Answer» E. | |
| 3. |
What will be the volume of air at 327°C if its volume at 27°C is 1.5 m³/ mt? |
| A. | m³/ mt. |
| B. | .5 m³/ mt. |
| C. | 8 m³/ mt. |
| D. | m³/ mt. |
| Answer» B. .5 m³/ mt. | |
| 4. |
The overall thermal efficiency of an ideal gas turbine plant is (where r = Pressure ratio) |
| A. | ɣ-1 |
| B. | - r ɣ-1 |
| C. | - (1/r) ɣ-1/ɣ |
| D. | - (1/r) ɣ/ɣ-1 |
| Answer» D. - (1/r) ɣ/ɣ-1 | |
| 5. |
In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in ________ of the piston. |
| A. | ne stroke |
| B. | wo strokes |
| C. | hree strokes |
| D. | our strokes |
| Answer» C. hree strokes | |
| 6. |
The ratio of isentropic work to Euler’s work is known as |
| A. | ompressor efficiency |
| B. | sentropic efficiency |
| C. | uler |
| D. | ressure coefficient |
| Answer» E. | |
| 7. |
Isothermal compression though most efficient, but is not practicable because |
| A. | t requires very big cylinder |
| B. | t does not increase pressure much |
| C. | t is impossible in practice |
| D. | ompressor has to run at very slow speed to achieve it |
| Answer» E. | |
| 8. |
A jet engine has |
| A. | o propeller |
| B. | ropeller in front |
| C. | ropeller at back |
| D. | ropeller on the top |
| Answer» B. ropeller in front | |
| 9. |
The work-done on a compressor will be minimum if air is taken from |
| A. | he atmosphere |
| B. | source at 0° C |
| C. | source of low temperature air |
| D. | source of high temperature air |
| Answer» D. source of high temperature air | |
| 10. |
In a double acting compressor, the air is compressed |
| A. | n one cylinder |
| B. | n two cylinders |
| C. | n a single cylinder on both sides of the piston |
| D. | n two cylinders on both sides of the piston |
| Answer» D. n two cylinders on both sides of the piston | |
| 11. |
In a closed cycle gas turbine, the air is compressed |
| A. | sothermally |
| B. | olytropically |
| C. | sentropically |
| D. | one of these |
| Answer» D. one of these | |
| 12. |
The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is |
| A. | ressure drop across the valves |
| B. | uperheating in compressor |
| C. | learance volume and leakages |
| D. | ll of these |
| Answer» E. | |
| 13. |
In a jet engine, the air-fuel ratio is |
| A. | 0:1 |
| B. | 0:1 |
| C. | 0:1 |
| D. | 0:1 |
| Answer» E. | |
| 14. |
The overall efficiency of the compressed air system is the |
| A. | atio of shaft output of the air motor to the shaft input to the compressor |
| B. | atio of shaft input to the compressor to the shaft output of air motor |
| C. | roduct of shaft output of air motor and shaft input to the compressor |
| D. | one of the above |
| Answer» B. atio of shaft input to the compressor to the shaft output of air motor | |
| 15. |
Standard air is the air at |
| A. | tmospheric conditions at any specific location |
| B. | 0°C and 1 kg/cm² and relative humidity 36% |
| C. | °C and standard atmospheric conditions |
| D. | 5°C and 1 kg/cm² |
| Answer» C. °C and standard atmospheric conditions | |
| 16. |
In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of |
| A. | acuum |
| B. | tmospheric air |
| C. | ompressed air |
| D. | xygen alone |
| Answer» D. xygen alone | |
| 17. |
Which of the following plants is smallest and lightest for generating a given amount of power? |
| A. | as turbine plant |
| B. | etrol engine |
| C. | iesel engine |
| D. | olar plant |
| Answer» B. etrol engine | |
| 18. |
The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the |
| A. | diabatic temperature drop in the stage |
| B. | otal temperature drop |
| C. | otal temperature drop in the stage |
| D. | otal adiabatic temperature drop |
| Answer» D. otal adiabatic temperature drop | |
| 19. |
The work ratio of simple gas turbine cycle depends on |
| A. | ressure ratio |
| B. | aximum cycle temperature |
| C. | inimum cycle temperature |
| D. | ll of the above |
| Answer» E. | |
| 20. |
Reheating in a multistage expansion gas turbine ________ compressor work. |
| A. | as no effect on |
| B. | ecreases |
| C. | ncreases |
| D. | one of these |
| Answer» C. ncreases | |
| 21. |
Compression efficiency is compared against |
| A. | deal compression |
| B. | diabatic compression |
| C. | sentropic compression |
| D. | sothermal compression |
| Answer» E. | |
| 22. |
The output of a gas turbine is 300 KW and its efficiency is 20 percent, the heat supplied is |
| A. | 000 KW |
| B. | 5 KW |
| C. | 00 KW |
| D. | 50 KW |
| Answer» C. 00 KW | |
| 23. |
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. | emain same |
| B. | ecrease |
| C. | ncrease |
| D. | one of the above |
| Answer» D. one of the above | |
| 24. |
The ratio of the discharge pressure to the inlet pressure of air is called |
| A. | ompression ratio |
| B. | xpansion ratio |
| C. | ompressor efficiency |
| D. | olumetric efficiency |
| Answer» B. xpansion ratio | |
| 25. |
To avoid moisture troubles, the compressed air main line should |
| A. | ise gradually towards the point of use |
| B. | rop gradually towards the point of use |
| C. | e laid vertically |
| D. | e laid exactly horizontally |
| Answer» C. e laid vertically | |
| 26. |
The air power of the compressor is also known as |
| A. | ndicated power |
| B. | rake power |
| C. | rictional power |
| D. | one of these |
| Answer» B. rake power | |
| 27. |
A centrifugal compressor works on the principle of |
| A. | onversion of pressure energy into kinetic energy |
| B. | onversion of kinetic energy into pressure energy |
| C. | entripetal action |
| D. | enerating pressure directly |
| Answer» C. entripetal action | |
| 28. |
The volume of air sucked by the compressor during its suction stroke is called |
| A. | ree air delivery |
| B. | ompressor capacity |
| C. | wept volume |
| D. | one of these |
| Answer» D. one of these | |
| 29. |
The weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is |
| A. | ame |
| B. | igher |
| C. | ower |
| D. | one of these |
| Answer» D. one of these | |
| 30. |
For perfect intercooling in a two stage compressor |
| A. | ₂/p₁ = p₃/p₂ |
| B. | ₁/p₃ = p₂/p₁ |
| C. | ₁ = p3 |
| D. | ₁ = p₂ p3 |
| Answer» B. ₁/p₃ = p₂/p₁ | |
| 31. |
A closed cycle gas turbine works on |
| A. | arnot cycle |
| B. | ankine cycle |
| C. | ricsson cycle |
| D. | oule cycle |
| Answer» E. | |
| 32. |
Gas turbine works on |
| A. | rayton or Atkinson cycle |
| B. | arnot cycle |
| C. | ankine cycle |
| D. | ricsson cycle |
| Answer» B. arnot cycle | |
| 33. |
Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be |
| A. | .03 kg/cm² |
| B. | .06 kg/cm² |
| C. | .00 kg/cm² |
| D. | .53 kg/cm² |
| Answer» D. .53 kg/cm² | |
| 34. |
The inter-cooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p₁ = Intake pressure of air, p₂ = Inter-cooler pressure, and p₃ = Delivery pressure of air) |
| A. | ₂ = p₁ × p₃ |
| B. | ₂ = p₁/p₃ |
| C. | ₂ = p₁ × p₂ |
| D. | ₂ = p₃/p₁ |
| Answer» D. ₂ = p₃/p₁ | |
| 35. |
The volume of air delivered in a medium capacity air compressor per unit time is |
| A. | .1 to 1.2 m³/s |
| B. | .15 to 5 m³/s |
| C. | bove 5 m³/s |
| D. | one of these |
| Answer» C. bove 5 m³/s | |
| 36. |
Water gas is produced by |
| A. | arbonisation of coal |
| B. | assing steam over incandescent coke |
| C. | assing air and a large amount of steam over waste coal at about 65°C |
| D. | artial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast |
| Answer» C. assing air and a large amount of steam over waste coal at about 65°C | |
| 37. |
Producer gas is produced by |
| A. | arbonisation of coal |
| B. | assing steam over incandescent coke |
| C. | assing air and a large amount of steam over waste coal at about 65°C |
| D. | artial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast |
| Answer» E. | |
| 38. |
In air compressors, free air delivery means the |
| A. | ctual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions |
| B. | olume of air delivered by the compressor |
| C. | olume of air sucked by the compressor during its suction stroke |
| D. | one of the above |
| Answer» B. olume of air delivered by the compressor | |
| 39. |
The compressor efficiency is the |
| A. | sothermal H.P/indicated H.R |
| B. | sothermal H.P./shaft H.R |
| C. | otal output/air input |
| D. | ompression work/motor input |
| Answer» B. sothermal H.P./shaft H.R | |
| 40. |
When the outlet angle from the rotor of a centrifugal compressor is more than 90°, then the blades are said to be |
| A. | orward curved |
| B. | ackward curved |
| C. | adial |
| D. | one of these |
| Answer» B. ackward curved | |
| 41. |
The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature. |
| A. | qual to |
| B. | ess than |
| C. | ore than |
| D. | one of these |
| Answer» D. one of these | |
| 42. |
The assumption made in two stage compression with inter-cooler is that |
| A. | here is no pressure drop in the inter-cooler |
| B. | he compression in both the cylinders is polytropic |
| C. | he suction and delivery of air takes place at constant pressure |
| D. | ll of the above |
| Answer» E. | |
| 43. |
The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turbine and fixed higher and lower temperature) with increase in pressure ratio will |
| A. | ncrease first at fast rate and then slow |
| B. | ncrease first at slow rate and then fast |
| C. | ecrease continuously |
| D. | irst increase, reach maximum and then decrease |
| Answer» E. | |
| 44. |
The ratio of work-done per cycle to the stroke volume of the compressor is known as |
| A. | ompressor capacity |
| B. | ompression ratio |
| C. | ompressor efficiency |
| D. | ean effective pressure |
| Answer» E. | |
| 45. |
A compressor mostly used for supercharging of I.C. engines is |
| A. | adial flow compressor |
| B. | xial flow compressor |
| C. | oots blower |
| D. | eciprocating compressor |
| Answer» B. xial flow compressor | |
| 46. |
The mass of gas turbine per kW developed is about ________ as that of an I.C. engine. |
| A. | ame |
| B. | ne-half |
| C. | ne fourth |
| D. | ne sixth |
| Answer» E. | |
| 47. |
An after-cooler is used to |
| A. | emove impurities from air |
| B. | educe volume of air |
| C. | ause moisture and oil vapour to drop out |
| D. | ool the air |
| Answer» D. ool the air | |
| 48. |
In gas turbines, high thermal efficiency is obtained in |
| A. | losed cycle |
| B. | pen cycle |
| C. | oth of the above |
| D. | losed/open depending on other considerations |
| Answer» B. pen cycle | |
| 49. |
Which one of the following is the effect of blade shape on performance of a centrifugal compressor? |
| A. | ackward curved blades has poor efficiency |
| B. | ackward curved blades lead to stable performance |
| C. | orward curved blades has higher efficiency |
| D. | orward curved blades produce lower pressure ratio |
| Answer» E. | |
| 50. |
The material commonly used for air craft gas turbine is |
| A. | tainless steel |
| B. | igh alloy steel |
| C. | uralumin |
| D. | imken, Haste alloys |
| Answer» E. | |