E-PolyLearning

666. In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction xf = 0.2. The mixture splits into an extract phase E and a raf-finate phase R containing A at xB = 0.5 and xR = 0.05 respectively. The total mass of the extract phase is (in Kg)
a. 6.89
b. 8.89
c. 10
d. 8.25
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Answer: (b).8.89

667. Penetration theory states that the mass transfer co-coefficient is equal to (where, De is diffusivity and 't' is time)
a. (De.t)^1/2
b. (De/t)^1/2
c. (4De/πt)^1/2
d. (4De/t)
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Answer: (c).(4De/πt)^1/2

668. Reboiler is considered as one theoretical plate, because
a. of the assumption that vapour and liquid leaving the reboiler are in equilibrium.
b. vapour is recycled to the column.
c. reboiler itself contains one plate.
d. none of these.
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Answer: (a).of the assumption that vapour and liquid leaving the reboiler are in equilibrium.