Mass Transfer MCQs

Question 1

When the feed to a distillation column is a saturated liquid, slope of the feed line is

Accepted Answer

Infinity

Answer

Zero

Answer

Unity

Answer

None of these

Question 2

The critical moisture content in case of drying indicates the __________ rate period.

Accepted Answer

Beginning of falling

Answer

Beginning of constant

Answer

End of falling

Answer

None of these

Question 3

During drying of a solid, the critical moisture content increases with

Accepted Answer

Both B and C

Answer

Decreased drying rate

Answer

Increased thickness of the solid

Answer

Increased drying rate

Question 4

Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as

Accepted Answer

K ∝ D

Answer

K ∝ $$\sqrt {	ext{D}} $$

Answer

K ∝ D 1.5

Answer

K ∝ D 2

Question 5

Can the efficiency of a plate in the distillation tower be greater than 100%?

Accepted Answer

Never

Answer

Yes

Answer

Normally not; but is possible if infinite number of plates are put

Answer

Yes ; if the reflux ratio is maximum

Question 6

Solvent used in extractive distillation

Accepted Answer

Forms a low boiling azeotrope

Answer

Is of low volatility

Answer

Forms a high boiling azeotrope

Answer

Does not alter the relative volatility of the original components

Question 7

Tower diameter may be decreased by

Accepted Answer

Use of increased tray spacing

Answer

Using higher reflux ratio

Answer

Increasing the liquid flow rate

Answer

Increasing the vapour flow rate

Question 8

In distillation columns, the number of bubble caps per tray primarily depends upon the

Accepted Answer

Allowable gas and liquid velocities

Answer

Allowable liquid velocity

Answer

Allowable gas velocity

Answer

Feed composition

Question 9

Decoction refers to the use of solvent

Accepted Answer

At its boiling point

Answer

At ambient temperature

Answer

In its vapor form

Answer

None of these