250 Steam Boiler and Engines Questions and Answer (MCQ) PDF

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Steam Boiler and Engines Questions and Answer (MCQ) PDF

1. The state of vapor under saturation condition is described by
(a) pressure alone
(b) temperature alone
(c) pressure and temperature
(d) pressure and dryness fraction
(e) dryness fraction alone.
Ans: d

2. Pick up the wrong statement about critical condition of steam
(a) latent heat is zero
(b) liquid directly becomes steam
(c) specific volume of steam and liquid is same
(d) this is the maximum pressure limit
(e) all properties of liquid and steam are same.
Ans: d

3. Water boils when its vapour pressure
(a) equals that of the surroundings
(b) equals 760 mm of mercury
(c) equals to atmospheric pressure
(d) equals the pressure of water in the container
(e) boiling has ^nothing to do with vapour pressure.
Ans: a

4. Mechanical equivalent of heat for 1 kcal or Joule’s equivalent is equal to
(a) 421 kgm
(b) 421 kgm
(c) 539 kgm
(d) 102 kgm
(e) 75 kgm.
Ans: a

5. Equivalent evaporation of water is the evaporation “for a feed water supply at 100°C
(a) and its corresponding conversion into dry saturated steam at 100°C and 1.033 kg/cm2
(b) and its corresponding conversion into dry steam at desired boiler pressure
(c) conversion into steam at atmospheric condition
(d) conversion into steam at the same pres-sure at which feed water is supplied
(e) none of the above.
Ans: a

6. The evaporation of 15.653 kg of water per hour from and at 100°C is called
(a) evaporative capacity
(b) factor of evaporation
(c) equivalent evaporation
(d) one boiler h.p.
(e) boiler efficiency.
Ans: d

7. The increase in pressure
(a) lowers the boiling point of a liquid
(b) raises the boiling point of a liquid
(c) .does not affect the boiling point of a liquid
(d) reduces its volume
(e) none of the above.
Ans: b

8. During polytropic process
(a) heat transfer takes place across cylinder walls
(b) work is done
(c) steam may be wet, dry or super heated after expansion
(d) all of the above
(e) none of the above.
Ans: d

9. Hygrometery deals with the
(a) Hygroscopic substances
(b) water vapour in air
(c) temperature of air
(d) pressure of air
(e) density measurement.
Ans: b

10. 1 kg.m is equal to
(a) 9.81 Joules
(b) All Joules
(c) 427 Joules
(d) 102 Joules
(e) 539 Joules.
Ans: a

11. If partial pressure of air and steam be pa andps respectively in a condenser, then according to Dalton’s law, the pressure in condenser is equal to
(a) Ps-Pa
(b) pa-ps
(C) Pa+P,
Ans: c

12. Equivalent evaporation is the amount of water evaporated in a boiler from and at
(a) 0°C
(b) 100°C
(c) saturation temperature at given pressure
(d) room temperature
(e) 20°C.
Ans: b

13. The specific volume of steam with increase in pressure decreases
(a) linearly
(b) slowly first and then rapidly
(c) rapidly first and then slowly
(d) inversely
(e) none of the above.
Ans: c

14. The equivalent evaporation of a boiler is a measure to compare
(a) the given boiler with the model
(b) the two different boilers of the same make
(c) two different makes of boilers operat¬ing under the same operating conditions
(d) two boilers of same make but operaing under different conditions
(e) any type of boilers operating under any conditions.
Ans: e

15. The coal requirement per kW hour generation in the thermal power plant is of the order of
(a) 0.1 to 0.2 kg
(b) 0.2 to 0.4 kg
(c) 0.6 to 0.8 kg
(d) 1.0 to 1.5 kg
(e) 1.5 to 2 kg.
Ans: c

16. Sublimation region is the region where
(a) solid and vapour phases are in equi-librium
(b) solid and liquid phases are in equilibrium
(c) liquid and vapour phases are in equilibrium
(d) solid, liquid and vapour phases are in equilibrium
(e) none of the above.
Ans: a

17. The dry saturated steam at very low pressure, (5-10 kg/cm2) when throttled to atmosphere will become
(a) wet
(b) superheated
(c) remain dry satruated
(d) dry
(e) none of the above.
Ans: b

18. 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
(e) none of the above.
Ans: b

19. The dry saturated steam at very high pressure (150-200 kg/cm2) when throttled to atmosphere will become
(a) wet
(b) superheated
(c) remain dry saturated
(d) dry
(e) none of the above.
Ans: a

20. In a throttling process
(a) steam temperature remaisn constant
(b) steam pressure remains constant
(c) steam enthalpy remains constant
(d) steam entropy remains constant
(e) steam volume remains constant.
Ans: c

21. In a throttling process
(a) heat transfer takes place
(b) work is done by the expanding steam
(c) internal energy of steam changes
(d) all of the above
(e) none of the above.
Ans: e

22. The pressure at which latent heat of vaporisation of water is zero, is
(a) below atmospheric pressure
(b) 1 kg/cm2
(c) 100 kg/cm2
(d) 170 kg/cm2
(e) 225.6 kg/cm2.
Ans: e

23. Latent heat of dry steam at atmospneric pressure is equal to
(a) 539 kcal/kg
(b) 539 BTU/lb
(c) 427 kcal/kg
(d) 100 kcal/kg
(e) 471 kcal/kg.
Ans: a

24. The latent heat of steam with increase of pressure
(a) remains same
(b) increases
(c) decreases
(d) behaves unpredictably
(e) none of the above.
Ans: c

25. Stoichiometric quantity of air is the
(a) air present in atmosphere at NTP conditions
(b) air required for complete combustion of fuel with no excess air
(c) air required for optimum combustion so as to have reasonable excess air
(d) air required to convert CO into C02
(e) air required to form an explosive mixture.
Ans: b

26. One kg of steam sample contains 0.8 kg dry steam; it’s dryness fraction is
(a) 0.2
(b) 0.8
(c) 1.0
(d) 0.6
(e) 0.5.
Ans: b

27. If a steam sample is nearly in dry condition, then its dryness fraction can be most accurately determined by
(a) throttling calorimeter
(b) separating calorimeter
(c) combined separating and throttling calorimeter
(d) bucket calorimeter
(e) none of the above.
Ans: a

28. If xx and x2 be the dryess fractions obtained in separating calorimeter and throttling calorimeter respectively, then the actual dryness fraction of steam will be
(a) xxx2
(b) x, + x2
Ans: a

29. 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
(e) 1.0.
Ans: c

30. On Mollier chart, flow through turbine is represented by ‘
(a) horizontal straight line
(b) vertical straight line
(c) straight inclined line
(d) curved line
(e) none of the above.
Ans: b

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