E-PolyLearning

36. At minimum reflux ratio for a given separation
a. number of plates is zero.
b. number of plates is infinity.
c. minimum number of the theoretical plates is required.
d. separation is most efficient.
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Answer: (b).number of plates is infinity.

37. The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________
a. 1
b. 0.5
c. 10
d. 0
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Answer: (a).1

38. Dew point of a gas-vapour mixture
a. increases with temperature rise.
b. decreases with temperature rise.
c. decreases with decrease in pressure.
d. increases with increase in pressure.
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Answer: (c).decreases with decrease in pressure.

39. In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor.
a. increases with increase in
b. is one at unity value of
c. both (a) and (b)
d. neither (a) nor (b)
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Answer: (c).both (a) and (b)

40. Which of the following plays an important role in problems of simultaneous heat and mass transfer ?
a. Lewis number
b. Schmidt number
c. Prandtl number
d. Sherwood number
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Answer: (a).Lewis number