Mass Transfer MCQs

Question 1

Entrainer used in azeotropic distillation should

Accepted Answer

Form a low boiling azeotrope with one of the constituents of the mixture

Answer

Form a new azeotrope of low relative volatility with one of the constituents of the mixture

Answer

Have high latent heat of vaporisation

Answer

Have high viscosity to provide high tray efficiency

Question 2

$$\frac{{{{	ext{N}}_{{	ext{Sc}}}}}}{{{{	ext{N}}_{{	ext{Pr}}}}}}$$ is called the

Accepted Answer

Lewis number

Answer

Psychrometric ratio

Answer

Sherwood number

Answer

Stantan number

Question 3

The humid volume may be increased by increasing the

Accepted Answer

Both A & B

Answer

Temperature at constant humidity

Answer

Humidity at constant temperature

Answer

Neither A nor B

Question 4

Plate towers are preferred to packed towers, when large temperature changes are involved, because of the reason that the

Accepted Answer

Packing may be crushed due to thermal expansion/contraction of the components of the equipments

Answer

Pressure drop in the equipment will be very high

Answer

Viscosity variation of the fluids may cause channeling/flooding

Answer

None of these

Question 5

Use of raschig rings in place of crushed stones as packing in packed beds (other things being same)

Accepted Answer

Decreases pressure drop, increases surface area

Answer

Increases pressure drop, increases surface area

Answer

Increases pressure drop, decreases surface area

Answer

Decreases pressure drop, decreases surface area

Question 6

Prandtl number for water at 20°C is about

Accepted Answer

7

Answer

70

Answer

0.7

Answer

150

Question 7

Blowdown in a cooling tower

Accepted Answer

Means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities

Answer

Increases the scale forming tendencies of water

Answer

Is undesirable

Answer

All of the above

Question 8

Boiling point diagram is

Accepted Answer

Affected by pressure

Answer

Not affected by pressure

Answer

A plot of temperature vs. liquid composition

Answer

A plot of temperature vs. vapour composition

Question 9

Bollman extractor

Accepted Answer

Is used for extraction of oil from oilseed

Answer

Is a static bed leaching equipment

Answer

Is a centrifugal extractor

Answer

Employs only counter-current extraction