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m tn2 Flashcards

1
Q

With increase in gas rate, the number of transfer units, NtoG,
for a fixed degree of absorption by a fixed amount of solvent
A. increases
B. decreases
C. decreases linearly
D. remains unaffected

A

A

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2
Q

Schmidt number is given by
A. u/p Dab
B. Re.Pe
C. Sh x Pe
D. Re/Pe

A

A

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3
Q

The caking of crystals can be prevented by
A. maintaining high critical humidity.
B. maintaining low critical humidity.
C. coating the product with inert material.
D. both (a) and (c)

A

d

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4
Q

Boiling point diagram is
A. not affected by pressure.
B. affected by pressure.
C. a plot of temperature vs. liquid composition.
D. a plot of temperature vs. vapour composition

A

B

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5
Q

Steam distillation is used to
A. reduce the number of plates.
B. avoid thermal decomposition of a component.
C. increase the efficiency of separation.
D. increase the total pressure of distillation.

A

B

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6
Q

Freundlich equation applies to the adsorption of solute from
A. dilute solutions, over a small concentration range.
B. gaseous solutions at high pressure.
C. concentrated solutions.
D. none of these.

A

A

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7
Q

For ethanol-water system, the lowering of distillate quality
from 95% to 92% will cause __________ plate requirement.
A. no change in theoretical
B. marginal decrease in the number of
C. major decrease in the number of
D. none of these

A

B

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8
Q

The apex of an equilateral-triangular coordinate (in ternary
liquid system) represents a/an
A. pure component
B. binary mixture
C. ternary mixture
D. insoluble binary system

A

A

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9
Q

Which of the following psychrometric processes is followed by
water vapour laden unsaturated air, when it is passed through
solid or liquid adsorbent ?
A. Cooling and dehumidification.
B. Heating and dehumidification at almost constant wet
bulb temperature.
C. Dehumidification with dry bulb temperature
remaining constant.
D. None of these.

A

B

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10
Q

The diffusivity (D) in a binary gas mixture is related to the
pressure (P) as
A. D ∝ P0.5
B. D ∝ 1/ P0.5
C. D ∝ 1/P
D. D ∝ 1/ P1.5

A

D

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11
Q

A slurry is to be dried to produce flaky solid. Which dryer would
you recommend?
A. Spray dryer
B. Drum dryer
C. Rotary dryer
D. Dielectric dryer

A

A

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12
Q

In gas-liquid contact operation, the number of ideal stages,
. This is true when the stripping factor ‘S’ is
A. S > 1
B. S < 1
C. S = 1
D. S = ∞

A

A

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13
Q

The cooling effect in a cooling tower can not be increased by
A. increasing the air velocity over the wet surfaces.
B. reducing the humidity of entering air.
C. lowering the barometric pressure.
D. none of these.

A

D

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14
Q

The value of NA/(NA + NB) for steady state molecular diffusion
of gas ‘A’ through non-diffusing gas ‘B’ is
A. 1
B. ∞
C. 0.5
D. 2

A

A

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15
Q

The humid volume may be increased by increasing the
A. temperature at constant humidity.
B. humidity at constant temperature.
C. both (a) and (b).
D. neither (a) nor (b)

A

C

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16
Q

When the mixture to be distilled has a very high boiling point
and the product material is heat sensitive, the separation
technique to be used is __________ distillation.
A. continuous
B. steam
C. azerotropic
D. none of these

A

B

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17
Q

Large scale drying of wheat is done in a __________ dryer.
A. fluidised bed
B. spouted bed
C. tray
D. vacuum rotary

A

B

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18
Q

Azeotropic distillation is employed to separate
A. constant boiling mixture.
B. high boiling mixture.
C. mixture with very high relative volatility.
D. heat sensitive materials.

A

A

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19
Q

The drying time between fixed moisture content within
diffusion controlled ‘falling rate period’ is proportional to
(assuming that drying occurs from all surfaces of the solid)
(where, T = thickness of the solid )
A. √𝑇
B. T
C. T2
D. T3

A

C

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20
Q

At the boiling point of the liquid at the prevailing pressure, the
saturated absolute humidity becomes
A. 1
B. 0
C. ∞
D. none of these

A

C

prevailing pressure = infinity

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21
Q

Use of natural draft cooling tower is practised, when the air
has low
A. humidity
B. temperature
C. both ‘a’ & ‘b’
D. neither ‘a’ nor ‘b’

A

C

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22
Q

Pressure drop through plate tower as compared to that
through packed tower, for the same duty will be
A. less
B. more
C. equal
D. either (a) or (b); depends on the packing height

A

B

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23
Q

Dimension of mass diffusivity is the same as that of
A. kinematic viscosity
B. dynamic viscosity
C. surface tension
D. pressure

A

A

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24
Q

Dorr thickener is an equipment used for
A. classification
B. sedimentation
C. clarification
D. leaching

A

B

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25
Q

Steam distillation is used to separate
A. azeotropes.
B. high boiling substances from nonvolatile impurities.
C. heat sensitive materials.
D. mixtures of low relative volatility.

A

B

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26
Q

In distillation where q is defined as the moles of liquid flow in
the stripping section per mole of feed introduced, for saturated
liquid feed
A. q > 1
B. q < 1
C. q = 1
D. q = 0

A

C

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27
Q

Which of the following is an undesirable property in a tower
packing ?
A. Large surface per unit volume.
B. Large free cross-section.
C. Low weight per unit volume.
D. Large weight of liquid retained.

A

D

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28
Q

Water entrained by circulating air in cooling towers is termed
as
A. drift
B. blow down
C. vapor load
D. none of these.

A

A

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29
Q

Humidity chart is useful for the solution of problems
concerning condensation, vaporisation and air conditioning. At
a given dry bulb temperature, value of humidity obtained from
the humidity chart directly, is in terms of __________ humidity.
A. molal
B. relative
C. percentage
D. none of these

A

A

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30
Q

A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was
dried from both sides under constant drying rate conditions. It
took 1500 seconds for the weight of the sheet to reduce to
1.05 kg. Another 1m x 1m x 1cm flat sheet of the same
material is to be dried from one side only.Under the same
constant drying rate conditions, the time required for drying (in
seconds) from its initial weight of 19.2 kg to 17.6 kg is
A. 1000
B. 1500
C. 2000
D. 2500

A

A

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31
Q

With increase in temperature, the rate of leaching increases,
because the
A. diffusivity of solute increases.
B. viscosity of solvent decreases.
C. thermal conductivity of solute increases.
D. none of these.

A

A

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32
Q

The Kundsen diffusivity is proportional to (where, T = absolute
temperature)
A. √𝑇
B. T2
C. T
D. T4

A

A

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33
Q

In case of constant underflow extraction operation, the
__________ at all solute concentration.
A. solids are drained to the same extent
B. ratio of the insoluble to solution is constant
C. both(a) & (b)
D. neither (a) nor (b)

A

C

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34
Q

In an absorption coloumn, the flooding velocity for random
packing is __________ that for stacked/regular packing.
A. greater than
B. smaller than
C. equal to
D. either (a), or (b) ; depends on the type of packing

A

B

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35
Q

The relation among various mass transfer co-efficients
(M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C.
for equimolar counter diffusion with concentration & mole
fraction respectively as the driving force. and, Kp = M.T.C. for
diffusion of a gas through a stagnant inert gas with pressure
as driving force.)
A. Kc = Kp = Km
B. Kc = Kp/RT = Km . RT/P
C. Kc = Kp . RT = Km . RT/p
D. none of these

A

C

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36
Q

With increase in temperature, the leaching rate increases
because of the
A. increased diffusivity.
B. decreased viscosity of liquid.
C. both (a) and (b).
D. neither (a) nor (b).

A

C

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37
Q

Leaching of uranium ore and gold ore is done in
A. centrifugal extractor
B. Pachuka tanks
C. Bollman extractor
D. none of these

A

B

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38
Q

In a binary distillation column, if the feed contains 40 mole %
vapour, the q line will have a slope of
A. 1.5
B. -0.6
C. -1.5
D. 0.6

A

C

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39
Q

Blowdown in a cooling tower
A. means discarding a small fraction of circulating water
to prevent and limit the concentration of salt and
impurities.
B. increases the scale forming tendencies of water.
C. is undesirable.
D. all (a), (b) & (c).

A

D

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40
Q

During constant rate period, the rate of drying decreases with
the
A. decrease in air temperature
B. increase in air humidity
C. both (a) and (b)
D. neither (a) nor (b)

A

C

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41
Q

Antibiotics are best handled in a
A. Podbielniak extractor.
B. sieve tray contractor.
C. rotating disc contactor.
D. pulsed column extractor.

A

A

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42
Q

The fixed cost of a distillation column at minimum reflux ratio
is
A. minimum
B. infinite
C. optimum
D. none of these

A

B

fixed cost=infinite

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43
Q

__________ extractor uses centrifugal force for separating the
two phases.
A. Treybal
B. Schiebel
C. Podbielniak
D. None of these

A

C

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44
Q

Pick out the wrong statement.
A. Mechanical agitation is required, if the system has
low interfacial tension.
B. Seive tray towers are generally used for systems
having low interfacial tension.
C. When Henry’s law constant is very small, then the
mass transfer rate is controlled by the gas film
resistance.
D. Taylor-Prandtl analogy for heat and mass transfer
considers the transfer through both laminar and
turbulent layers.

A

A

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45
Q

Acetic acid will be most economically separated from a dilute
solution of acetic acid in water by
A. solvent extraction
B. continuous distillation
C. evaporation
D. absorption

A

A

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46
Q

Design calculation for multiple component distillation is done
by
A. Ponchon-Savarit method
B. Mccabe-Thiele method
C. enthalpy concentration method
D. tray to tray calculations.

A

D

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47
Q

Pick out the wrong statement. Generally for physical
adsorption, a gas of
A. higher molecular weight is adsorbed in preference to
a gas of low molecular weight.
B. high critical temperature is adsorbed in preference to
a gas of low critical temperature.
C. low volatility is adsorbed in preference to a gas of
high volatility.
D. none of these.

A

D

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48
Q

To get high tray efficiency
A. interfacial surface between liquid and gas phase
should be large.
B. time of contact between the two phases should be
less.
C. gas velocity should be very low.
D. liquid entrainment should be severe.

A

A

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49
Q

The mass transfer co-efficient for a solid sphere of radius ‘a’
dissolving in a large volume of quiescent liquid, in which D is
the diffusivity of solute, is
A. D/a
B. D/2a
C. proportional to √𝐷
D. dependent on the Reynolds number

A

D

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50
Q

In most of the mechanically agitated liquid-liquid extractors,
baffles or horizontal compartmental plates are provided, which
helps in
A. reducing the axial mixing.
B. increasing the rate of extraction.
C. maintaining the concentration difference between the
two phases.
D. all ‘a’, ‘b’ & ‘c’.

A

D

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51
Q

In a vapor-liquid contacting equipment, the overall gas phase
mass transfer co-efficient (M.T.C), KG is related to individual
co-efficients (KG and KL) as
A. kG = 1/ KG = M/KL
B. 1/KG= 1/KG+M/KL
C. 1/KG= 1/KL+ M/KG

A

B

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52
Q

Solvent extraction is the terminology applied to the liquid-liquid
extraction, which is preferred for the separation of the
components of liquids, when
A. extracting solvent is cheaply & abundantly available.
B. one of the liquid components is heat sensitive.
C. viscosity of liquid components is very high.
D. one of the liquid components has very high affinity
towards the solvent.

A

D

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53
Q

Inside the distillation column, the
A. driving force for the vapour flow is the pressure drop.
B. liquids are not always at their bubble points.
C. pressure increases gradually from bottom to the top
of the column.
D. none of these

A

A

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54
Q

Diffusivity in concentrated solutions differs from that in dilute
solutions, because of the changes in
A. viscosity with concentration.
B. degree of ideality of the solution.
C. both (a) and (b).
D. neither (a) nor (b).

A

C

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55
Q

Which of the following is not a continuous drier ?
A. Drum drier
B. Spray drier
C. Tunnel drier
D. Tray drie

A

D

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56
Q

Molecular seives are regenerated by heating to ________ °C.
A. < 150
B. 200-330
C. 500
D. 1000

A

B

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57
Q

Humidification involves mass transfer between a pure liquid
phase and a fixed gas, which is
A. insoluble in the liquid
B. soluble in the liquid
C. non-ideal in nature
D. at a fixed temperature

A

A

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58
Q

_________ is the temperature at which a gas-vapor mixture
becomes saturated, when cooled at constant total pressure
out of contact with a liquid.
A. Dew point
B. Bubble point
C. Dry bulb temperature
D. Wet bulb temperature

A

A

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59
Q

Rate of leaching increases with increasing
A. temperature
B. viscosity of solvent
C. pressure
D. size of the solid

A

A

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60
Q

An azeotropic mixture is a __________ mixture.
A. binary
B. ternary
C. constant boiling point
D. none of these

A

C

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61
Q

Pick out the wrong statement.
A. In the McCabe-Thiele diagram for binary distillation,
vertical feed line represents saturated liquid feed and
horizontal feed line represents saturated vapour
feed.
B. In small columns, local efficiency is larger than
Murphree efficiency; in large columns local efficiency
is smaller than Murphree efficiency.
C. For Laminar flow over a plate of length L, the local
mass transfer co-efficient at a distance L from the
leading edge is 1.5 x 10-2m/s. Then the average
mass transfer co-efficient for the plate is 2 x 10-2m/s.
D. The concentration and hydrodynamic boundary
layers over a flat plate are of equal thickness, if
Schmidt number is equal to unity.

A

C

62
Q

Occurrence of ‘case hardening’ during drying of a high
moisture solid cake __________ the drying rate.
A. increases
B. decreases
C. does not affect
D. exponentially increases

A

B

63
Q

In continuous distillation, the internal reflux ratio (Ri) and the
external reflux ratio (Re) are related as
A. 𝑅= RE/1-RE
B. 𝑅= 1-RE/RE
C. Ri = Re
D. 𝑅= RE/1+RE

A

D

64
Q

In a counter-current extractor, as the axial mixing increases,
the extraction efficiency
A. increases
B. decreases
C. remains unchanged
D. depends on the pressure of the system

A

B

65
Q

Large scale drying of sugar is done in a __________ dryer.
A. spouted bed
B. tray
C. rotary
D. Truck

A

C

66
Q

Heat sensitive materials like certain pharmaceuticals and food
stuffs can be dried in a/an __________ dryer.
A. indirect tray
B. spray
C. freeze
D. none of these

A

C

67
Q

In extractive distillation, solvent is
A. added to alter the relative volatility of the mixture.
B. of high volatility.
C. present in overhead stream.
D. of high viscosity to give high tray efficiency

A

A

68
Q

Radioactive nuclear waste is treated in
A. mixer-settler extractor
B. rotating-disc contactor
C. pulsed column extractor
D. Bollman extractor

A

C

69
Q

_________ temperature is the steady state temperature
attained by a small amount of liquid evaporating into a large
quantity of unsaturated gas-vapor mixture.
A. Dry bulb
B. Wet bulb
C. Dew point
D. none of these

A

B

70
Q

The drying time between fixed moisture contents within the
‘constant rate period’ is proportional to (assuming that drying
occurs from all surfaces of the solid) (where, T = thickness of
the solid )
A. √𝑇
B. T
C. T1.5
D. T3
_

A

B

71
Q

________ equation applies to diffusivities in liquids.
A. Gilliland
B. Hirschfelder
C. Wilke and Chang
D. none of these

A

A

72
Q

A packed tower compared to a plate tower for a particular
mass transfer operation
A. incurs smaller pressure drop.
B. allows installation of cooling coils.
C. is less costly when built in large sizes/diameters.
D. is more suitable, if suspended solids are present in
fluid streams.

A

A

73
Q

Which of the following is the most commonly used leaching
solvent in vegetable oil industry ?
A. Phenol
B. Hexane
C. Furfurol
D. Liquid SO2

A

B

74
Q

In an absorber, HETP does not vary with the
A. flow rate of liquid
B. flow rate of gas
C. type and size of packing
D. none of these

A

D

75
Q

Large quantity of silica gel is normally dried in a __________
dryer.
A. freeze
B. through circulation
C. rotary vacuum
D. tray

A

B

76
Q

For the same system, if the same liquid used in an absorber
is decreased, the tower height will
A. increase
B. decrease
C. remain unaffected
D. decrease or increase ; depends on the type of liquid

A

A

77
Q

Hydrogenation of oil is carried out in a/an __________ in
Vanaspati manufacturing plant.
A. agitated vessel
B. sieve tray column
C. bubble cap column
D. packed tower

A

A

78
Q

Sides of equilateral-triangular co-ordinates (on which ternary
liquid system is plotted) represent
A. a pure component.
B. a binary mixture.
C. a ternary mixture.
D. partially miscible ternary system

A

B

79
Q

In distillation column design, the McCabe-Thiele procedure is
inadequate and a Ponchan-Savarit procedure is needed,
when
A. saturated feed is not used.
B. an azeotrope forms.
C. the latent heat of vaporisation of the more and less
volatile components are greatly different.
D. a total condenser is used.

A

D

80
Q

In an interphase mass transfer process, the lesser the
solubility of a given solute in a liquid, the higher are the
chances that the transfer process will be
A. liquid phase resistance-controlled.
B. gas phase resistance controlled.
C. impossible.
D. driven by a non-linear driving force.

A

B

81
Q

As the reflux ratio decreases, the
A. separation becomes more efficient.
B. number of plates increases.
C. column diameter increases.
D. none of these.

A

B

82
Q

Which of the following equipments is not used for gas
dispersion?
A. Agitated vessels
B. Bubble cap tray towers
C. Perforated sieve tray towers
D. Spray towers

A

D

83
Q

One mole feed of a binary mixture of a given composition is
flash vaporised at a fixed P and T. If Raoult’s law is obeyed,
then changing the feed composition would effect
A. the product composition but not the fraction
vaporised.
B. the product composition as well as the fraction
vaporised.
C. the fraction vaporised but not the product
composition.
D. neither the product composition nor the fraction
vaporised.

A

C

84
Q

The equation, NA= DAB*P/RTZ (Y1-Y2)
is for
A. steady state equimolar counter diffusion
B. Fick’s first law of diffusion
C. steady state diffusion for stagnant case
D. liquid M.T.C. by penetration theory.

A

A

85
Q

With increase in the liquid flow rate at a fixed gas velocity in a
randomly packed counter current gas-liquid absorption
column, the gas pressure drop
A. decreases
B. remains unchanged
C. increases
D. decreases exponentially

A

C

86
Q

The equation, NA= DAB*PT/RTZ pBM (Pa1-Pa2)
is for
A. Fick’s second law of diffusion.
B. stready state diffusion for stagnant case.
C. liquid M.T.C. by Higbie penetration theory.
D. none of these.

A

B

87
Q

Which of these columns incurs the lowest pressure drop ?
A. Packed column (with stacked packing)
B. Packed column (with dumped packing)
C. Bubble plate colu

A

A

88
Q

In the desorption of highly soluble gas from the liquid, the main
resistance will be in the __________ phase.
A. gas
B. liquid
C. both (a) & (b)
D. neither (a) nor (b)

A

B

main resitance = liquid

89
Q

If G = insoluble gas in gas stream and L = non-volatile solvent
in liquid stream, then the slope of the operating line for the
absorber is
A. L/G
B. G/L
C. always < 1
D. none of these

A

A

90
Q

Which of the following remains constant during evaporative
cooling process with recirculated water supply ?
A. Relative humidity
B. Partial pressure of vapour
C. Wet bulb temperature
D. None of these

A

C

91
Q

For stripping of a gas in a counter current stripper, the
operating line
A. lies above the equilibrium curve.
B. lies below the equilibrium curve.
C. can lie above or below the equilibrium curve.
D. is always parallel to the equilibrium curve.

A

C

counter current stripper = above or below

92
Q

Which of the following same diameter columns gives lowest
pressure drop per unit height ?
A. Bubble-cap column
B. Sieve-plate column
C. Packed column (stacked)
D. Randomly packed column

A

C

93
Q

Diffusion in concentrated solutins differs from that in dilute
solutions, because of the change in the __________ with the
concentration of the solution.
A. degree of ideality
B. viscosity
C. both ‘a ‘& ‘b’
D. neither ‘a’ nor ‘b’

A

C

94
Q

Capacity of a rotary dryer depends on its
A. r.p.m
B. inclination with ground surface
C. both (a) and (b)
D. neither (a) nor (b)

A

C

95
Q

Stage efficiency in a leaching process depends on the
A. time of contact between the solid and the solution
B. rate of diffusion of the solute through the solid and
into the liquid
C. both (a) and (b)
D. vapour pressure of the solution

A

C

96
Q

Operating velocity in a packed tower is usually __________
the flooding velocity.
A. half
B. twice
C. equal to
D. more than

A

A

97
Q

The Knudsen diffusivity is dependent on the

molecular velocity only.
pore radius of the catalyst only.
molecular mean free path only.
molecular velocity and por radius of the catalyst.

A

D

98
Q

Minimum possible diameter of a packed coloumn is decided
mainly by the
A. flooding
B. gas viscosity
C. liquid density
D. liquid hold up

A

A

99
Q

Solvent used in extractive distillation
A. is of low volatility.
B. forms a low boiling azeotrope.
C. forms a high boiling azeotrope.
D. does not alter the relative volatility of the original
components.

A

B

extractive = low boiling

100
Q

The cooling effect in a cooling tower can be speeded up by
A. increasing the air velocity and area of exposed wet
surface.
B. reducing the barometric pressure.
C. reducing the humidity of the air.
D. all (a), (b) and (c).

A

D

101
Q

The following plot gives the saturated humidity (He) versus
temperature (T).Line joining (H1, T1) and (H2, T2) is the
constant enthalpy line. Choose the correct one from among
the alternatives A, B, C and D.
A. T1-Dew point temp; T2-Dry bulb temp; T3-Wet bulb
temp.
B. T1-Dew point temp; T2-Wet bulb temp; T3-Dry bulb
temp.
C. T1-Wet bulb temp; T2-Dry bulb temp; T3-Dew point
temp.
D. T1-Dry bulb temp; T2-Wet bulb temp; T3-Dew point
temp.

A

D

102
Q

When both the fluids flow concurrently in an absorber, the
slope of the operating line is
A. - ve
B. + ve
C. 1
D. -1

A

A

concurrently = -ve

103
Q

The percentage humidity is less than the relative humidity only
at __________ percent humidity.
A. zero
B. hundred
C. both zero and hundred
D. none of these

A

C

104
Q

Back-trapping in a distillation column
A. increases tray efficiency.
B. decreases tray efficiency.
C. reduces pressure drop.
D. is desirable, as it provides improved vapour-liquid
contact.

A

B

105
Q

Flooding in a vapor-liquid contacting equipment occurs in a
tray, when the pressure drop through a tray is __________ the
liquid head available in the downcomer.
A. less than
B. more than
C. same as
D. very much less

A

B

106
Q

Milk is dried usually in a __________ dryer.
A. freeze
B. spray
C. tray
D. rotary

A

B

107
Q

At a given equilibrium pressure, with increase in temperature,
the concentration of adsorbed gas on solid adsorbant
A. increases
B. decreases
C. remains unchanged
D. increases exponentially

A

B

solid adsorbant = decrease

108
Q

Which of the following adsorbent is used to decolourise yellow
glycerine ?
A. Silica gel
B. Alumina
C. Fuller’s earth
D. Activated carbon

A

D

109
Q

Which of the following liquid temperature (T) Vs. vapor-gas
mixture enthalpy (H) diagram is valid for humidification
operation?
(JUST SEARCH)

A

B

110
Q

In a distillation column, with increase in the reflux ratio, the
heat removed in the cooler
A. increases.
B. decreases.
C. remains unaffected.
D. and the heat required in reboiler decreases.

A

A

111
Q

Pick out the wrong statement.
A. Constant pressure distillation can not separate an
azeotropic mixture.
B. Relative volatility of a binary mixture changes
appreciably with the minor change in temperature.
C. The relative volatility of a binary mixture at azeotropic
composition is unity.
D. Flash distillation is practised on wide spread scale in
petroleum refinery.

A

B

112
Q

Which of the following is not a unit of mass transfer coeff. ?
A. moles transfered/ timeareamole fxn
B. moles transfered/ timeareapressure
C. moles transfered/ timeareamass a/mass b
D. None of these

A

D

113
Q

The falling rate period in the drying of a solid is char. by
A. increase in rate of drying.
B. increasing temperatures both on the surface and
within the solid.
C. decreasing temperatures.
D. none of these.

A

B

114
Q

In which of the following unit operations, the selectivity is an
important parameter ?
A. Distillation
B. Solvent extraction
C. Absorption
D. None of these

A

B

115
Q

Which of the following is an undesirable characteristic for the
solvent used in gas absorption ?
A. Low vapor pressure
B. Low viscosity
C. High gas solubility
D. None of these

A

D

116
Q

Which of the following equipments is not used for liquid
dispersion ?
A. Wetted wall towers
B. Packed towers
C. Venturi scrubbers
D. Agitated vessels

A

D

117
Q

Diameter of raschig rings used in packed tower in industry is
normally around __________ inches.
A. 2
B. 8
C. 12
D. 18

A

A

118
Q

The diffusion co-efficient in m2 /s. of acetic acid in benzene
(liquid in liquid) is
A. 2.09 x 10-4
B. 2.09 x 10-5
C. 2.09 x 10-9
D. 2.09 x 10-12

A

C

119
Q

Pick out the correct statement.
A. For identical gas flow rates, less pressure drop
occurs through a plate tower than through a packed
tower.
B. Plate column can handle greater liquid loads without
flooding than packed column, but the liquid hold up
is more in the case of plate column.
C. For the same duty, plate columns weigh less than
packed columns.
D. all (a), (b) and (c).

A

D

120
Q

Pick out the wrong statement.
A. The Reynolds analogy for mass transfer is given by
Lewis relation and is applicable, when Schmidt
number is one.
B. Sherwood number for flow in pipes can be expressed
as the ratio of the concentration gradient at wall to
the overall concentration difference.
C. According to film theory for equimolar counter
diffusion, the mass transfer coefficient is given
by 𝐷
(b)P - 3, Q - 2
D. The z-component of the total mass flux of a
component A in binary mixture of A and B is given by - Dab’.dCA/dz.

A

D

121
Q

In case of non-ideal gases and liquids, the molal diffusivity
A. varies inversely as the pressure.
B. varies directly as the pressure.
C. is independent of pressure.
D. is equal to the volumetric diffusivity.

A

C

122
Q

Condensation of a vapour-gas mixture just begins, when
(where, p = partial pressure of the vapour P = vapour pressure
of the liquid )
A. p = P
B. p&raquo_space;P
C. p < P
D. p &laquo_space;P

A

A

123
Q

__________ number indicates the ratio of the rates of the
heat and mass transfer incase of a cooling tower.
A. Sherwood
B. Stanton
C. Lewis
D. Peclet

A

C

124
Q

The expression, y(1 - x)/x(1 - y) is for
A. absorption factor
B. relative volatility
C. selectivity
D. Murphree efficiency

A

B

125
Q

In physical terms, Schmidt number means
A. thermal diffusivity/mass diffusivity.
B. thermal diffusivity/momentum diffusivity.
C. momentum diffusivity/mass diffusivity.
D. mass diffusivity/thermal diffusivity.

A

C

126
Q

In case of liquids, the binary diffusivity is proportional to
(where, T = temperature)
A. T
B. √𝑇
C. T2
D. 1/T

A

A

binary diffysivity = T

127
Q

The diffusivity, DAB (for component A diffusing in B) is equal to
the diffusivity DBA (for component B diffusing in A) for a binary
mixture of
A. Newtonion liquids
B. non-Newtonion liquids
C. ideal gases
D. real gases

A

C

128
Q

During dehumidification of unsaturated air wet bulb
temperature & partial pressure of vapor are not constant.
However, during evaporative cooling process with recirculated
water supply, the __________ remains constant.
A. wet bulb temperature
B. partial pressure of water vapor
C. relative humidity
D. none of these

A

A

129
Q

Advantage of continuous drying over batch drying is that the
A. drying cost per unit weight of dried product is less.
B. product with more uniform moisture content is
produced.
C. equipment size required is smaller.
D. all ‘a’, ‘b’ & ‘c’

A

D

130
Q

Mass transfer co-efficient is directly proportional to DAB0.5,
according to __________ theory.
A. penetration
B. surface renewal
C. film
D. none of these

A

A

directly proportional = penetration

131
Q

Sand is dried in foundaries in a ___ drier.
A. rotary
B. fluidized bed
C. vacuum
D. spray

A

B

132
Q

Which of the following employs an accessory known as ‘drift
eliminator’?
A. Multiple effect evaporator.
B. Mechanical draft cooling tower.
C. Rotary dryer.
D. Rotating disc contactor.

A

B

133
Q

Pick out the correct statement.
A. Higher hold up of the solid in the rotary dryer results
in better exposure of the solids to the gas.
B. The ‘Hatta number’ is important in problems involving
gas absorption without chemical reaction.
C. For a non-reacting binary mixture of ideal gases, the
partial pressure distribution of both components is
linear in the case of steady state equimolal counter
diffusion.
D. Total reflux in case of distillation operation requires
infinite number of plates for a binary system
separation.

A

C

134
Q

Humid volume is the total volume in m3 of 1 kg of
A. vapour laden gas at 1 atm. and room temperature.
B. gas plus its accompanying vapour at 1 atm. and room
temperature.
C. gas plus its accompanying vapour at 1 atm. and gas
temperature.
D. vapour laden gas at 1 atm. and gas temperature.

A

C

135
Q

Diameter to height ratio for a rashig ring is
A. 1
B. 0.5
C. 2
D. 8

A

A

136
Q

The equipment used in the extraction of highly corrosive radio
active liquids is
A. pulse column
B. spray column
C. mixer settler
D. baffle tower

A

A

137
Q

In case of absorption & stripping, the interface of the liquid & gas
phases are present in equilibrium, when the diffusional
resistance of __________ is zero.
A. Interface
B. gas phase
C. liquid phase
D. all ‘a’, ‘b’ & ‘c’

A

A

138
Q

With increase in temperature, the rate of extraction in leaching
(solid-liquid extraction system)
A. increases
B. decreases
C. remains unaffected
D. increases Linearly

A

A

139
Q

In a packed bed absorption column, the channelling will be
noted by the
A. increase in flow rate.
B. sharp drop in pressure drop.
C. sharp rise in pressure drop.
D. none of these.

A

B

140
Q

Gaseous diffusivity at atmospheric pressure is of the order of
__________ cm2/second.
A. 1
B. 1 to 5
C. 5 to 10
D. 10

A

A

141
Q

In liquid-liquid extraction, the number of phases at plait point is
A. 1
B. 2
C. 3
D. 4

A

A

142
Q

In a liquid-liquid extraction, 10 kg of a solution containing 2 kg
of solute C and 8 kg of solvent A is brought into contact with 10
kg of solvent B. Solvent A and B are completely immiscible in
each other whereas solute C is soluble in both the solvents. The
extraction process attains equilibrium. The equilibrium
relationship between the two phases is Y* = 0.9X, where Y* is
the kg of C/kg of B and X is kg of C/kg of A. Choose the correct
answer.
A. The entire amount of C is transferred to solvent B.
B. Less than 2 kg but more than 1 kg of C is transferred
to solvent B.
C. Less than 1 kg of C is transferred to B.
D. No amount of C is tranferred to B.

A

A

143
Q

The surface renewal frequency in Danckwerts’ model of mass
transfer is given by (KL: mass transfer co-efficient)
A. sqrt(K^2D)
B. KL^2.DA
C. KL^2/DA
D. KL/DA^2

A

A

144
Q

If Rm is the minimum reflux ratio, the optimum reflux ratio may
be around __________ Rm.
A. 1.2 to 1.5
B. 2.5 to 3
C. 3 to 4
D. 5

A

A

145
Q

In case of absorption, both the operating and equilibrium lines
will be straight for
A. isothermal operation.
B. dilute solutions.
C. dilute solutions and isothermal operation.
D. none of these.

A

C

146
Q

Unsaturated air (with dry bulb and wet bulb temperatures being
45°C and 25°C respectively) is passed through a water spray
chamber maintained at 23°C. The air will be cooled and
A. humidified with wet bulb temperature decreasing.
B. humidified at constant wet bulb temperature.
C. dehumidified.
D. none of these

A

A

147
Q

Mass transfer co-efficient varies as DAB0.5, according to the
__________ theory.
A. film
B. surface renewal
C. penetration
D. none of these

A

B

varies =film

148
Q

For an absorber, both equilibrium and operating line will be
straight for
A. concentrated solution and non-isothermal
operation.
B. dilute solution and non-isothermal operation.
C. dilute solution and isothermal operation.
D. concentrated solution and isothermal operation.

A

C

149
Q

A distillation column separates 10000 kg/hr of a benzene
toluene mixture as shown in the figure below:
In the figure xF, xD and xW represent the weight fraction of
benzene in the feed, distillate and residue respectively. The
reflux ratio is
A. 0.5
B. 0.6
C. 1.0
D. 2.0

A

B

150
Q

Humid volume, at a given temperature is a/an __________
function of humidity.
A. inverse
B. exponential
C. linear
D. Logarithmic

A

C

h trfs (13 decks)

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