26. 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
27. 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 saturated
(d) dry
(e) none of the above.
Ans: b
28. 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
29. 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
30. 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
31. 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
32. 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
33. 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
34. 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
35. At critical point, i.e. p=225.65 kg/cm2, the latent enthalpy of vaporization is
(a) maximum
(b) minimum
(c) zero
(d) depends on temperature also
(e) none of the above.
Ans: c
36. 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
37. 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
38. 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
39. 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
40. 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
41. The state of vapour 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
42. 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
43. 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 con-tainer
(e) boiling has ^nothing to do with vapour pressure.
Ans: a
45. 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
46. 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
47. 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
48. 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
49. During polytropic process
(a) heat transfer takes place across cylinder walls
(b) work is done
(c) steam may be wet, dry or superheated after expansion
(d) all of the above
(e) none of the above.
Ans: d
50. 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