Mass Transfer MCQs

Question 1

In case of __________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated.

Accepted Answer

Extractive

Answer

Molecular

Answer

Azeotropic

Answer

Flash

Question 2

The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called

Accepted Answer

Elutriation or elution

Answer

Decoction

Answer

Percolation

Answer

None of these

Question 3

Pick out the wrong statement.

Accepted Answer

According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by $$\sqrt {{{	ext{D}}_{{	ext{AB}}}}} $$ (b)P - 3, Q - 2

Answer

The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one

Answer

Sherwood number for flow in pipes can be expressed as the ratio of the concentration gradient at wall to the overall concentration difference

Answer

The z-component of the total mass flux of a component A in binary mixture of A and B is given by - Dab'.dC A /dz

Question 4

Which of the following processes is not an example of adsorption applied to gaseous separations?

Accepted Answer

Decolouration of yellow glycerene

Answer

Recovery of valuable solvent vapors from dilute mixture with air and other gases

Answer

Dehumidification of air and gas

Answer

Removal of objectionable odour and impurities from industrial gases

Question 5

As the reflux ratio decreases, the

Accepted Answer

Number of plates increases

Answer

Separation becomes more efficient

Answer

Column diameter increases

Answer

None of these

Question 6

Which of the following adsorbant is used in the refinning of sugar?

Accepted Answer

Bone charcoal

Answer

Wood charcoal

Answer

Silica gel

Answer

Activated clay

Question 7

Pick out the correct relationship. (where, R i = internal reflux ratio R o = external reflux ratio)

Accepted Answer

$$1 + {{	ext{R}}_{	ext{o}}} = \frac{{{{	ext{R}}_{	ext{o}}}}}{{{{	ext{R}}_{	ext{i}}}}}$$

Answer

$$1 - {{	ext{R}}_{	ext{o}}} = \frac{{{{	ext{R}}_{	ext{o}}}}}{{{{	ext{R}}_{	ext{i}}}}}$$

Answer

$$1 + {{	ext{R}}_{	ext{i}}} = \frac{{{{	ext{R}}_{	ext{o}}}}}{{{{	ext{R}}_{	ext{i}}}}}$$

Answer

$$1 - {{	ext{R}}_{	ext{i}}} = \frac{{{{	ext{R}}_{	ext{o}}}}}{{{{	ext{R}}_{	ext{i}}}}}$$

Question 8

When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,

Accepted Answer

All of the above

Answer

As the acetone concentration increases, the solubility curves approach each other

Answer

Both the phases become identical at a particular common point on both the solubility curves called the plait point

Answer

The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x - y curve used in distillation and absorption terminates on the x = y diagonal at the concentration of the plait point

Question 9

Stacked packing compared to dumped packing

Accepted Answer

Both A & B

Answer

Provides poorer contact between the fluids

Answer

Gives lower pressure drop

Answer

Gives higher pressure drop