Boiler Questions and Answers with PDF for Operator

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Boiler Questions and Answers with PDF for Operator

1. A wet vapor can be completely specified by
(a) pressure only
(b) temperature only
(c) dryness fraction only
(d) specific volume only
(e) pressure and dryness fraction.
Ans: e

2. On Mollier chart, the constant pressure lines
(a) diverge from left to right
(b) diverge from right to left
(c) are equally spaced throughout
(d) first rise up and then fall
(e) none of the above.
Ans: a

3. On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
(a) horizontal straight line
(b) vertical straight line
(c) straight inclined line
(d) curved line
(e) none of the above.
Ans: a

4. The bituminous coal is non-caking if its carbon content is
(a) 78-81%
(b) 81-85%
(c) 85-90%
(d) 90-95%
(e) 95-100%.
Ans: a

5. At critical point, i.e. p=225.65 kg/cm2, the latent enthalpy of vaporisation is
(a) maximum
(b) minimum
(c) zero
(d) depends on temperature also
(e) none of the above.
Ans: c

6. At which pressure the properties of water and steam become identical
(a) 0.1 kg/cm2
(b) 1 kg/cm2
(c) 100 kg/cm2
(d) 225.6 kg/cm2
(e) it is never possible.
Ans: d

7. In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is
(a) 40%
(b) 25%
(c) 50%
(d) 80%
(e)90%.
Ans: d

8. While steam expands in turbines, theoretically the entropy
(a) remains constant
(b) increases
(c) decreases
(d) behaves unpredictably
(e) none of the above.
Ans: a

9. Heating wet steam at constant temperature is heating it at constant
(a) volume
(b) pressure
(c) entropy
(d) enthalpy
(e) none of the above.
Ans: b

10. Adiabatic process is
(a) essentially an isentropic process
(b) non-heat transfer process
(c) reversible process
(d) constant temperature process
(e) constant enthalpy process.
Ans: b

11. For water, at pressures below atmospheric,
(a) melting point rises slightly and boiling point drops markedly
(b) melting point rises markedly and boiling point drops markedly
(c) melting point drops slightly and boiling point drops markedly
(d) melting point drops slightly and boiling point drops slightly
(e) none of the above.
Ans: a

12. At very low temperature, the melting and boiling temperatures become equal. This temperature is
(a) 373°K
(b) 273.16°K
(c) 303°K
(d) 0°K.
(e) 300°K.
Ans: b

13. The critical pressure at which latent heat of vaporisation is zero is
(a) 225.65 kgf/cm2
(b) 273 kgf/cm2
(c) 100 kgf/cm2
(d) 1 kgf/cm2
(e) – 1 kgf/cm2.
Ans: a

14. The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
(a) less
(b) more
(c) equal
(d) may be less or more depending on temperature
(e) unpredictable.
Ans: a

15. The saturation temperature of steam with increase in pressure increases
(a) linearly
(b) rapidly first and then slowly
(c) slowly first and then rapidly
(d) inversely
(e) none of the above.
Ans: b

16. 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 brick-ettes
(e) enriching carbon in the coal.
Ans: c

17. Coke is produced by
(a) pulverising coal in inert atmosphere
(b) heating wood in a limited supply of air at temperatures below 300GC
(c) strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
(d) binding the pulverised coal into brick-etts
(e) enriching carbon in the coal.
Ans: c

18. Heating of dry steam above saturation temperature is known as
(a) enthalpy
(b) superheating
(c) supersaturation
(d) latent heat
(e) super tempering.
Ans: b

19. Superheating of steam is done at
(a) constant volume
(b) constant temperature
(c) constant pressure
(d) constant entropy
(e) constant enthaply.
Ans: c

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