1000+ Steam Boilers, Engines, Nozzles & Turbines MCQ for JEE Main [Solved]

1. The artificial draught is produced by
A. Steam jet
B. Centrifugal fan
C. Chimney
D. Both (A) and (B)
Answer : D

2. A supercritical boiler is one that operates above the pressure and temperature of following values
A. 100 kg/cm² and 540°C
B. 1 kg/cm² and 100°C
C. 218 kg/cm² abs and 373°C
D. 218 kg/cm² abs and 540°C
Answer : C

3. The ultimate analysis of fuel lists
A. Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume
B. Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight
C. Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash
D. Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash
Answer : B

4. The function of a valve rod is
A. To provide reciprocating motion to the slide valve
B. To convert reciprocating motion of the piston into rotary motion of the crank
C. To convert rotary motion of the crankshaft into to and fro motion of the valve rod
D. To provide simple harmonic motion to the D-slide valve
Answer : D

5. The numbers of fire tubes in a Cochran boiler are
A. 75
B. 115
C. 165
D. 225
Answer : C

6. Water at pressure of 4 kg/cm² and 160°C temperature when exposed to atmosphere will
A. Boil
B. Flash i.e. get converted into steam
C. Remain as it was
D. Cool down
Answer : B

7. It is required to produce large amount of steam at low pressure. Which boiler should be used?
A. Pulverised fuel fired boiler
B. Cochran boiler
C. Lancashire boiler
D. Babcock and Wilcox boiler
Answer : C

8. In a nozzle, the effect of super-saturation is to
A. Decrease dryness fraction of steam
B. Decrease specific volume of steam
C. Increase the entropy
D. Increase the heat drop
Answer : C

9. De-Laval turbines are mostly used
A. Where low speeds are required
B. For small power purposes and low speeds
C. For large power purposes
D. For small power purposes and high speeds
Answer : D

10. Over fire burning is the phenomenon of
A. Supply of excess, air
B. Supply of excess coal
C. Burning CO and unburnts in upper zone of furnace by supplying more air
D. Fuel bed firing
Answer : C

11. Adiabatic process is
A. Essentially an isentropic process
B. Non-heat transfer process
C. Reversible process
D. Constant temperature process
Answer : B

12. When steam after doing work in the cylinder passes into a condenser, the engine is said to be a
A. Slow speed engine
B. Vertical steam engine
C. Condensing steam engine
D. Non-condensing steam engine
Answer : C

13. The biggest size of thermal power unit operating in India is
A. 30 MW
B. 60 MW
C. 100 MW
D. 500 MW
Answer : D

14. Which of the following statement is wrong?
A. Locomotive boiler is a water tube boiler
B. Water tube boilers are internally fired
C. Lamont boiler is a low pressure water tube boiler
D. All of the above
Answer : D

15. The three Ts for good combustion are
A. Temperature, time, and turbulence
B. Total air, true fuel, and turbulence
C. Thorough mixing, total air and temperature
D. Total air, time, and temperature
Answer : A

16. Bomb calorimeter is used to determine
A. Higher calorific value at constant volume
B. Lower calorific value at constant volume
C. Higher calorific value at constant pressure
D. Lower calorific value at constant pressure
Answer : A

17. The specific heat of superheated steam in kcal/kg is generally of the order of
A. 0.1
B. 0.3
C. 0.5
D. 0.8
Answer : C

18. Parson's reaction turbine is a __________ reaction turbine.
A. 40 percent
B. 50 percent
C. 60 percent
D. 70 percent
Answer : B

19. The velocity of flue gases (V) through the chimney under a static draught of (H') metres is given by
A. V = 2g H'
B. V = 2g/H'
C. V = H'/2g
D. V = 2gH'
Answer : A

20. In order to obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
A. Remain unaffected
B. Improve
C. Worsen
D. May improve/worsen depending on size
Answer : C

21. The difference between Cornish boiler and Lancashire boiler is that
A. Former is fire tube type and latter is water tube type boiler
B. Former is water tube type and latter is fire tube type
C. Former contains one fire tube and latter contains two fire tubes
D. None/of the above
Answer : C

22. Orsat meter is used for
A. Gravimetric analysis of the flue gases
B. Volumetric analysis of the flue gases
C. Mass flow of the flue gases
D. Measuring smoke density of flue gases
Answer : B

23. Stage efficiency is also known as
A. Diagram efficiency
B. Nozzle efficiency
C. Gross efficiency
D. None of these
Answer : C

24. The overall efficiency of thermal power plant is
A. Boiler efficiency, turbine efficiency, generator efficiency
B. All the three above plus gas cycle efficiency
C. Carnot cycle efficiency
D. Regenerative cycle efficiency
Answer : A

25. The ratio of the volume at cut-off to the swept volume is called
A. Cut-off ratio
B. Expansion ratio
C. Clearance ratio
D. None of these
Answer : A

26. The function of injector used in small capacity boilers is to
A. Create vacuum
B. Inject chemical solution in feed pump
C. Pump water, similar to boiler feed pump
D. Add make up water in the system
Answer : C

27. The factor of evaporation for all boilers is always
A. Equal to unity
B. Less than unity
C. Greater than unity
D. None of these
Answer : C

28. Efficiency of Rankine cycle can be increased by
A. Decreasing initial steam pressure and temperature
B. Increasing exhaust pressure
C. Decreasing exhausts pressure
D. Increasing the expansion ratio
Answer : A

29. Which is not the correct statement about moisture in coal?
A. Inherent moisture and surface moisture are different things
B. In some coals moisture may be present up to 40%
C. Some moisture in coal helps in better burning which is not possible with completely dry coal
D. It increases thermal efficiency
Answer : D

30. Carbonisation of coal is the process of
A. Pulverising coal in inert atmosphere
B. Heating wood in a limited supply of air at temperatures below 300°C
C. Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
D. Binding the pulverised coal into briquettes
Answer : C

31. By compounding the expansion of steam in two or more cylinders, the ratio of expansion
A. Does not change
B. Increases
C. Decreases
D. None of these
Answer : C

32. When the cross-section of a nozzle increases continuously from entrance to exit, it is called a
A. Divergent nozzle
B. Convergent nozzle
C. Convergent-divergent nozzle
D. None of these
Answer : A

33. The velocity of whirl at outlet for an axial discharge turbine is
A. Minimum
B. Maximum
C. Zero
D. None of these
Answer : C

34. In forced recirculation type boiler,
A. Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
B. Water is supplied in drum and through down comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam
C. Feed pump is employed to supplement natural circulation in water wall type furnace
D. Water is converted into steam in one pass without any recirculation
Answer : C

35. For burning 1 kg of carbon to CO as per chemically correct combustion, amount of air required is
A. 1 kg
B. 4/3 kg
C. 8/3 kg
D. 2 kg
Answer : B

36. Thermal efficiency of a thermal power plant is of the order of
A. 15 %
B. 20 %
C. 30 %
D. 45 %
Answer : C

37. A throttle governed steam engine develops 15 kW with 280 kg per hour of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW will be nearly
A. 150 kg/h
B. 210 kg/h
C. 280 kg/h
D. 340 kg/h
Answer : D

38. One kg of steam sample contains 0.8 kg dry steam; Its dryness fraction is
A. 0.2
B. 0.8
C. 1.0
D. 0.6
Answer : B

39. The reheat factor depends upon
A. Initial pressure and superheat
B. Exit pressure
C. Turbine stage efficiency
D. All of these
Answer : D

40. A steam nozzle converts
A. Heat energy of steam into kinetic energy
B. Kinetic energy into heat energy of steam
C. Heat energy of steam into potential energy
D. Potential energy into heat energy of steam
Answer : A

41. In a receiver type compound engine, the high pressure and low pressure cylinders
A. Have common piston rod
B. Are set at 90°
C. Have separate piston rods
D. Are set in V-arrangement
Answer : C

42. A binary vapour plant consists of
A. Steam turbine
B. Steam condenser
C. Mercury boiler
D. All of these
Answer : D

43. A _________ in a boiler is used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit.
A. Blow off cock
B. Fusible plug
C. Stop valve
D. Safety valve
Answer : B

44. The draught produced by a steam jet issuing from a nozzle placed in the ash-pit under the fire grate of the furnace is called
A. Induced steam jet draught
B. Chimney draught
C. Forced steam jet draught
D. None of these
Answer : C

45. The critical pressure gives the velocity of steam at the throat
A. Equal to the velocity of sound
B. Less than the velocity of sound
C. More than the velocity of sound
D. None of these
Answer : A

46. The critical pressure ratio for initially wet steam is
A. 0.546
B. 0.577
C. 0.582
D. 0.601
Answer : C

47. Hard coke is produced by carburisation of coal at
A. Atmospheric temperature
B. 500-600°C
C. 700-850°C
D. 950-1100°C
Answer : D

48. The flow through a nozzle is regarded as
A. Constant volume flow
B. Constant pressure flow
C. Isothermal flow
D. Isentropic flow
Answer : D

49. Cut-off governing as compared to throttle governing is
A. Less efficient and less economical
B. Less efficient and more economical
C. More efficient and less economical
D. More efficient and more economical
Answer : D

50. Pulverised fuel is used for
A. Better burning
B. More calorific value
C. Less radiation loss
D. Medium sized units
Answer : A