Section 1

Question 1

Mass transfer rate between two fluid phases does not necessarily depend on the __________ of the two phases.

Answer 1

chemical properties

Question 2

In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is

Answer 2

0.50

Question 3

Fenske equation determines the

Answer 3

minimum number of theoretical plates.

Question 4

The term “cooling range” in a cooling tower refers to the difference in the temperature of

Answer 4

hot water entering the tower and the cooled water leaving the tower.

Question 5

Which of the following is the most suitable for extraction in a system having very low density difference ?

Answer 5

Centrifugal extractor

Question 6

Total reflux in a distillation operation requires minimum

Answer 6

number of plates

Question 7

The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is

Answer 7

+ve

Question 8

Fenske’s equation for determining the minimum number of theoretical stages in distillation column holds good, when the

Answer 8

relative volatility is reasonably constant.

Question 9

When the temperature and humidity of air is low, we usually use __________ draft cooling tower.

Answer 9

natural

Question 10

Pick out the correct statement.
A. In case of liquid-liquid extraction, no separation is possible, if the selectivity of the solvent used is unity.
B. With increase in temperature, the selectivity of the solvent used in solvent extraction decreases.
C. The selectivity of solvent used in solvent extraction is unity at the plait point.
D. all (a), (b) and (c).

Answer 10

D. all (a), (b) and (c).

Question 11

__________ columns are used for liquid dispersion in a continuous gas phase.

Answer 11

PACKED

Question 12

13.
Overall efficiency of the distillation column is

Answer 12

the ratio of number of ideal plates to actual plates.

Question 13

Which is the controlling factor for a drum drier?

Answer 13

heat transfer

Question 14

Drying operation under vacuum is carried out to

Answer 14

reduce drying temperature.

Question 15

Air initially at 101. 3 kPa and 40°C and with a relative humidity of 50%, is cooled at constant pressure to 30°C. The cooled air has a

Answer 15

higher relative humidity

Question 16

Separation of two or more components of a liquid solution can not be achieved by

Answer 16

absorption

Question 17

At minimum reflux ratio for a given separation

Answer 17

number of plates is infinity.

Question 18

Relative humidity is the ratio of the

Answer 18

partial pressure of the vapour to the vapour pressure of the liquid at gas temperature.

Question 19

In batch distillation with constant reflux, overhead product composition __________ with time.

Answer 19

decreases

Question 20

Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre.

Answer 20

electrical resistance

Question 21

Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1°F is called the

Answer 21

specific heat

Question 22

To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate)

Answer 22

increase ‘S’ and decrease ‘G’.

Question 23

The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________

Answer 23

1

Question 24

Dew point of a gas-vapour mixture

Answer 24

decreases with decrease in pressure.

Question 25

Which of the following plays an important role in problems of simultaneous heat and mass transfer ?

Answer 25

Lewis number

Question 26

In case of an absorber, the operating

Answer 26

line always lies above the equilibrium curve.

Question 27

As the reflux ratio in a distillation coloumn is increased from the minimum, the

Answer 27

total cost first decreases and then increases.

Question 28

Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve)

Answer 28

S1/S2

Question 29

A plait point is the point on the solubility curve, where the tie line reduces to a point. What is the number of plait point for a ternery system containing twopairs of partially miscible liquids ?

Answer 29

0

Question 30

Make up water is required in a cooling tower to replace the water lost by
evaporation
drift
blowdown and leakage
all (a), (b) and (c)

Answer 30

all (a), (b) and (c)

Question 31

Which of the following quantities need not be fixed before starting the design of a co-current absorber ?

Answer 31

Flow rate of entering liquid

Question 32

Mass transfer co-efficient of liquid is

Answer 32

affected more by temperature than that for gases.

Question 33

Absorption accompanied with chemical reaction is exemplified by the absorption of

Answer 33

SO2 in alkaline solution.

Question 34

Which of the following unit operations makes use of Thiele-Geddes equation ?

Answer 34

Multicomponent distillation.

Question 35

Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty ?

Answer 35

Wetted wall column

Question 36

The equipment frequently used for adiabatic humidification-cooling operation with recirculating liquid is

Answer 36

spray chamber

Question 37

Chemisorption (chemical adsorption) is

Answer 37

an irreversible phenomenon.

Question 38

The rate of solid-liquid extraction is limited by the
A. phase change of the solute as it dissolves in the solvent.
B. diffusion of the solute through the solvent in the pores to the outside of the particle.
C. diffusion of the solute from the solution in contact with the particle to the main bulk of the solution.
D. all ‘a’, ‘b’ & ‘c’.

Answer 38

D. all ‘a’, ‘b’ & ‘c’.

Question 39

Raoult’s law applies to the

Answer 39

solvents.

Question 40

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

Answer 40

allowable gas and liquid velocities.

Question 41

.
In distillation, overhead product contains

Answer 41

any number of components

Question 42

With increase in pressure, the relative volatility for a binary system

Answer 42

DECREASES

Question 43

Low viscosity absorbent is preferred for reasons of
rapid absorption rates and good heat transfer characteristics.
improved flooding characteristics.
low pressure drop on pumping.
all (a), (b) and (c).

Answer 43

all (a), (b) and (c).

Question 44

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

Answer 44

K ∝ D