Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if____________________?

Mass transfer is accompanied by reaction

Diffusion of A is in stagnant medium B

Molecular mean free path is high

There is equimolar counter diffusion

Chemisorption (chemical adsorption) is_______________________?

Same as “Van der Waals” adsorption

Characterised by adsorption of heat

Channelling is most severe_____________________?

In towers packed randomly with crushed solids

In towers packed with stacked packing

In towers packed randomly with crushed solids

In dumped packing of regular units

Capacity of a rotary dryer depends on its __________________?

Inclination with ground surface

Bound moisture is that liquid which exerts an equilibrium vapor pressure ________________ that of the pure liquid at the given temperature ?

Either A. or B.; depends on the solid

Bollman extractor___________________?

Is a static bed leaching equipment

Is used for extraction of oil from oilseed

Employs only counter-current extraction

Blowdown in a cooling tower____________________?

Increases the scale forming tendencies of water

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

Increases the scale forming tendencies of water

Blowdown in a cooling tower__________________?

Increases the scale forming tendencies of water

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

Increases the scale forming tendencies of water

Binary distillation involves the mass transfer by ______________________ at the gas-liquid interface?

Unidirectional diffusion from liquid to gas phase

Unidirectional diffusion from gas to liquid phase

A counter diffusion at an almost equal molar rate

Batch tray dryers suffers from the disadvantage of______________________?

Non-uniform & low production rate

High labour cost & low heat economy

Back-trapping in a distillation column ?

Is desirable, as it provides improved vapour-liquid contact

At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid _______________ that in dry packed tower ?

Cannot be predicted as data are insufficient

At minimum reflux ratio for a given separation__________________?

Minimum number of the theoretical plates is required

At constant pressure, with increase of temperature, the dew point will ________________________?

Increase/decrease; depends on the temperature

At a fixed total pressure, humidity depends only on the _______________________?

Partial pressure of vapour in the mixture

As the reflux ratio in a distillation column is increased from the minimum, the______________________?

Liquid flow increases while the vapor flow decreases for a system

Slope of the operating line in stripping section decreases

Number of plates decreases very slowly first and then more and more rapidly

Total cost first decreases and then increases

Liquid flow increases while the vapor flow decreases for a system

As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages_______________________?

Can either increase or decrease, depends on the system

As the reflux ratio decreases, the_________________?

Separation becomes more efficient

As per Gilliland’s equation, the diffusivity is___________________?

Directly proportional to ‘T1.5’

Inversely proportional to ‘P’

Dependent on the molecular volume & molecular weight of components

An ideal tower packing should not _______________________?

Have low weight per unit volume

Have large surface area per unit volume

Hold up large amount of liquid in the packing

An example of elution is______________________?

Separation of sugar from sugar beet by hot water

Separation of uranium oxide from its ore by H2SO4 in a Pachuca tank

Separation of sugar from sugar beet by hot water

Dissolution of tannin out of tree barks by water

Recovery of vegetable oils from seeds

An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii) ____________________?

Composition of the residue remains unchanged

Less number of trays are required

Composition of the residue remains unchanged

More number of trays are required but the residue composition remains unchanged

More number of trays are required and the residue composition is more dilute in methanol

590 + Mcqs in Mass Transfer for Chemical in Chemical Engineering Page 11 McqOptions

501.	Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the ________________ number?
A.	Sherwood
B.	Schmidt
C.	Peclet
D.	Stanton
Answer» B. Schmidt

Discussion

502.	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 >>P
C.	p < P
D.	p << P
Answer» B. p >>P

Discussion

503.	Compound A is extracted from a solution of A + B into a pure solvent S. A Co-current unit is used for the liquid-liquid extraction. The inlet rate of the solution containing A is 200 moles of B/hr.m2 and the solvent flow, rate is 400 moles of S/m2. hr. The equilibrium data is represented by Y = 3X2 , where Y is in moles of a A/moles of B and X is in moles A/moles of S. The maximum percentage extraction achieved in the unit is_________________________?
A.	25%
B.	50%
C.	70%
D.	90%
Answer» C. 70%

Discussion

504.	Components, having widely different boiling point in a binary mixture, can be separated using ________________ distillation?
A.	Molecular
B.	Extractive
C.	Steam
D.	Simple
Answer» E.

Discussion

505.	Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if____________________?
A.	Mass transfer is accompanied by reaction
B.	Diffusion of A is in stagnant medium B
C.	Molecular mean free path is high
D.	There is equimolar counter diffusion
Answer» E.

Discussion

506.	_______________ columns are used for liquid dispersion in a continuous gas phase ?
A.	Packed
B.	Pulse
C.	Bubble cap
D.	Sieve plate
Answer» B. Pulse

Discussion

507.	_______________ column is used in gas absorption process ?
A.	Wetted wall
B.	Sieve/perforated tray
C.	Bubble cap
D.	Packed
Answer» E.

Discussion

508.	______________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids ?
A.	Wetted wall
B.	Packed
C.	Plate
D.	Spray
Answer» D. Spray

Discussion

509.	______________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction ?
A.	Packed
B.	Bubble
C.	Spray
D.	Tray
Answer» C. Spray

Discussion

510.	Coffee is prepared from coffee beans by leaching with____________________?
A.	Cold water
B.	Hot water
C.	Dilute hot caustic solution
D.	Naphtha
Answer» C. Dilute hot caustic solution

Discussion

511.	CO2 can be absorbed by____________________?
A.	Hot cupric oxide
B.	Heated charcoal
C.	Cold Ca(OH)2
D.	Alumina
Answer» C. Cold Ca(OH)2

Discussion

512.	Co-current absorbers are usually used when the gas to be dissolved in the liquid is ___________________?
A.	Sparingly soluble
B.	Highly soluble
C.	A pure substance
D.	A mixture
Answer» D. A mixture

Discussion

513.	Chemisorption (chemical adsorption) is_______________________?
A.	Same as “Van der Waals” adsorption
B.	Characterised by adsorption of heat
C.	An irreversible phenomenon
D.	A reversible phenomenon
Answer» D. A reversible phenomenon

Discussion

514.	Channelling in a packed tower results from the_____________________?
A.	High pressure drop
B.	Maldistribution of liquid
C.	Non-uniformity of packing
D.	Both B. and C.
Answer» E.

Discussion

515.	Channelling is most severe_____________________?
A.	In towers packed with stacked packing
B.	In towers packed randomly with crushed solids
C.	In dumped packing of regular units
D.	At very high liquid flow rate
Answer» B. In towers packed randomly with crushed solids

Discussion

516.	Capacity of a rotary dryer depends on its __________________?
A.	rpm
B.	Inclination with ground surface
C.	Both A. and B.
D.	Neither A. nor B.
Answer» D. Neither A. nor B.

Discussion

517.	Calculation of mass transfer co-efficient is mostly/normally done using ______________ theory?
A.	Surface renewal
B.	Film
C.	Penetration
D.	None of these
Answer» C. Penetration

Discussion

518.	Calcium ammonium nitrate (a fertiliser) is dried in a _________________ dryer?
A.	Rotary
B.	Vacuum
C.	Tunnel
D.	Tray
Answer» B. Vacuum

Discussion

519.	Bound moisture is that liquid which exerts an equilibrium vapor pressure ________________ that of the pure liquid at the given temperature ?
A.	Less than
B.	More than
C.	Equal to
D.	Either A. or B.; depends on the solid
Answer» B. More than

Discussion

520.	Bollman extractor___________________?
A.	Is a static bed leaching equipment
B.	Is used for extraction of oil from oilseed
C.	Is a centrifugal extractor
D.	Employs only counter-current extraction
Answer» C. Is a centrifugal extractor

Discussion

521.	Boiling point diagram is not affected by the ambient______________________?
A.	Pressure
B.	Humidity
C.	Temperature
D.	Both B. and C.
Answer» E.

Discussion

522.	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.
Answer» B. Increases the scale forming tendencies of water

Discussion

523.	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.
Answer» B. Increases the scale forming tendencies of water

Discussion

524.	Binary distillation involves the mass transfer by ______________________ at the gas-liquid interface?
A.	Unidirectional diffusion from liquid to gas phase
B.	Unidirectional diffusion from gas to liquid phase
C.	Either A. or B.
D.	A counter diffusion at an almost equal molar rate
Answer» E.

Discussion

525.	Berl saddle made of carbon cannot be used for ___________________?
A.	Alkalis
B.	SO2
C.	H2SO4
D.	Oxidising atmosphere
Answer» E.

Discussion

526.	Below is given an equilibrium moisture curve of a substance. State which regions represent free moisture and unbound moisture respectively ?
A.	II, III
B.	II, IV
C.	IV, III
D.	IV, II
Answer» B. II, IV

Discussion

527.	Batch tray dryers suffers from the disadvantage of______________________?
A.	High maintenance cost
B.	Non-uniform & low production rate
C.	High labour cost & low heat economy
D.	All ‘a’, ‘b’ & ‘c’
Answer» D. All ‘a’, ‘b’ & ‘c’

Discussion

528.	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
Answer» C. Reduces pressure drop

Discussion

529.	Azeotropism for ethyl alcohol-water system disappears by_____________________?
A.	Increasing temperature
B.	Decreasing pressure
C.	Increasing pressure
D.	No means
Answer» C. Increasing pressure

Discussion

530.	At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid _______________ that in dry packed tower ?
A.	Is greater than
B.	Is lower than
C.	Is same as
D.	Cannot be predicted as data are insufficient
Answer» B. Is lower than

Discussion

531.	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
Answer» D. None of these

Discussion

532.	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
Answer» D. None of these

Discussion

533.	At __________________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation?
A.	Operating
B.	Total
C.	Minimum
D.	Maximum permissible
Answer» C. Minimum

Discussion

534.	At minimum reflux ratio for a given separation__________________?
A.	Number of plates is zero
B.	Number of plates is infinity
C.	Minimum number of the theoretical plates is required
D.	Separation is most efficient
Answer» C. Minimum number of the theoretical plates is required

Discussion

535.	At equilibrium the concentration of water in vapour phase (C) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is_________________?
A.	0.0
B.	0.2
C.	0.4
D.	1.0
Answer» D. 1.0

Discussion

536.	At constant pressure, with increase of temperature, the dew point will ________________________?
A.	Increase
B.	Decrease
C.	Remain unchanged
D.	Increase/decrease; depends on the temperature
Answer» B. Decrease

Discussion

537.	At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent __________________?
A.	Increases
B.	Decreases
C.	Remains unchanged
D.	Increases exponentially
Answer» C. Remains unchanged

Discussion

538.	At a fixed total pressure, humidity depends only on the _______________________?
A.	Partial pressure of vapour in the mixture
B.	Heat capacity of the vapour
C.	Density of the vapour
D.	None of these
Answer» B. Heat capacity of the vapour

Discussion

539.	At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is ________________ percent.?
A.	100
B.	0
C.	50
D.	Between 0 and 100
Answer» C. 50

Discussion

540.	At 750°K and 1 atm, the approximate value of Schmidt number for air is_________________?
A.	0.01
B.	0.1
C.	1
D.	10
Answer» C. 1

Discussion

541.	As the reflux ratio in a distillation column is increased from the minimum, the______________________?
A.	Slope of the operating line in stripping section decreases
B.	Number of plates decreases very slowly first and then more and more rapidly
C.	Total cost first decreases and then increases
D.	Liquid flow increases while the vapor flow decreases for a system
Answer» D. Liquid flow increases while the vapor flow decreases for a system

Discussion

542.	As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages_______________________?
A.	Increase
B.	Decrease
C.	Remain unchanged
D.	Can either increase or decrease, depends on the system
Answer» C. Remain unchanged

Discussion

543.	As the reflux ratio decreases, the_________________?
A.	Separation becomes more efficient
B.	Number of plates increases
C.	Column diameter increases
D.	None of these
Answer» C. Column diameter increases

Discussion

544.	As per Gilliland’s equation, the diffusivity is___________________?
A.	Directly proportional to ‘T1.5’
B.	Inversely proportional to ‘P’
C.	Dependent on the molecular volume & molecular weight of components
D.	All A , B. & C.
Answer» E.

Discussion

545.	As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches ____________________?
A.	That of normal condensation
B.	Integral heat of adsorption
C.	Zero
D.	None of these
Answer» B. Integral heat of adsorption

Discussion

546.	An ideal tower packing should not _______________________?
A.	Have low weight per unit volume
B.	Have large surface area per unit volume
C.	Have large free cross-section
D.	Hold up large amount of liquid in the packing
Answer» E.

Discussion

547.	An example of elution is______________________?
A.	Separation of uranium oxide from its ore by H2SO4 in a Pachuca tank
B.	Separation of sugar from sugar beet by hot water
C.	Dissolution of tannin out of tree barks by water
D.	Recovery of vegetable oils from seeds
Answer» B. Separation of sugar from sugar beet by hot water

Discussion

548.	An Azeotropic mixture is a ________________ mixture?
A.	Binary
B.	Ternary
C.	Constant boiling point
D.	None of these
Answer» D. None of these

Discussion

549.	An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii) ____________________?
A.	Less number of trays are required
B.	Composition of the residue remains unchanged
C.	More number of trays are required but the residue composition remains unchanged
D.	More number of trays are required and the residue composition is more dilute in methanol
Answer» B. Composition of the residue remains unchanged

Discussion

550.	An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is ?
A.	9.21
B.	4.605
C.	100
D.	0.001
Answer» C. 100

Discussion

Explore topic-wise MCQs in Chemical Engineering.

Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the ________________ number?

Condensation of a vapour-gas mixture just begins, when (where, p = partial pressure of the vapour P = vapour pressure of the liquid) ?

Components, having widely different boiling point in a binary mixture, can be separated using ________________ distillation?

Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if____________________?

_______________ columns are used for liquid dispersion in a continuous gas phase ?

_______________ column is used in gas absorption process ?

______________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids ?

______________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction ?

Coffee is prepared from coffee beans by leaching with____________________?

CO2 can be absorbed by____________________?

Co-current absorbers are usually used when the gas to be dissolved in the liquid is ___________________?

Chemisorption (chemical adsorption) is_______________________?

Channelling in a packed tower results from the_____________________?

Channelling is most severe_____________________?

Capacity of a rotary dryer depends on its __________________?

Calculation of mass transfer co-efficient is mostly/normally done using ______________ theory?

Calcium ammonium nitrate (a fertiliser) is dried in a _________________ dryer?

Bound moisture is that liquid which exerts an equilibrium vapor pressure ________________ that of the pure liquid at the given temperature ?

Bollman extractor___________________?

Boiling point diagram is not affected by the ambient______________________?

Blowdown in a cooling tower____________________?

Blowdown in a cooling tower__________________?

Binary distillation involves the mass transfer by ______________________ at the gas-liquid interface?

Berl saddle made of carbon cannot be used for ___________________?

Below is given an equilibrium moisture curve of a substance. State which regions represent free moisture and unbound moisture respectively ?

Batch tray dryers suffers from the disadvantage of______________________?

Back-trapping in a distillation column ?

Azeotropism for ethyl alcohol-water system disappears by_____________________?

At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid _______________ that in dry packed tower ?

At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes______________________?

At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes_____________________?

At __________________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation?

At minimum reflux ratio for a given separation__________________?

At constant pressure, with increase of temperature, the dew point will ________________________?

At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent __________________?

At a fixed total pressure, humidity depends only on the _______________________?

At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is ________________ percent.?

At 750°K and 1 atm, the approximate value of Schmidt number for air is_________________?

As the reflux ratio in a distillation column is increased from the minimum, the______________________?

As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages_______________________?

As the reflux ratio decreases, the_________________?

As per Gilliland’s equation, the diffusivity is___________________?

As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches ____________________?

An ideal tower packing should not _______________________?

An example of elution is______________________?

An Azeotropic mixture is a ________________ mixture?

An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is ?