Mass Transfer MCQs

Question 1

Pick out the wrong statement.

Accepted Answer

Zirconia probe is used for the humidity measurement

Answer

Cellulose acetate membranes are used in dialysis process

Answer

Elutriation process refers to when the soluble material is largely concentrated on the surface of an insoluble solid and is simply washed off by the solvent

Answer

'Cascade' means a group of stages interconnected so that various streams flow from one to another

Question 2

Pick out the wrong statement

Accepted Answer

In actual practice, absorption is an en-dothermic process, while stripping is an exothermic process

Answer

Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance

Answer

In case of gas absorption, HETP is equal to HTU, when both the operating line & the equilibrium lines are parallel

Answer

Hatta number is important in case of gas absorption with chemical reaction

Question 3

Extraction of coffee from its seed is done by

Accepted Answer

Leaching

Answer

Liquid-liquid extraction

Answer

Extractive distillation

Answer

Steam distillation

Question 4

Perforated plate towers are unique for solvent extraction because, they provide

Accepted Answer

Repeated coalescence & redispersion of the drop phase

Answer

Higher contact area

Answer

Better contact of the phase

Answer

None of these

Question 5

An ideal tower packing should not

Accepted Answer

Hold up large amount of liquid in the packing

Answer

Have low weight per unit volume

Answer

Have large surface area per unit volume

Answer

Have large free cross-section

Question 6

In case of an ideal solution, the total vapor pressure varies __________ with the composition expressed as mole fraction,

Accepted Answer

Linearly

Answer

Inversely

Answer

Exponentially

Answer

None of these

Question 7

The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (K c ) for the same sytem is

Accepted Answer

10

Answer

100

Answer

5

Answer

1

Question 8

Heat sensitive materials like certain pharmaceuticals and food stuffs can be dried in a/an __________ dryer.

Accepted Answer

Freeze

Answer

Indirect tray

Answer

Spray

Answer

None of these

Question 9

J D factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by

Accepted Answer

N sh = 2

Answer

N st = 2

Answer

N sc = 2

Answer

None of these