For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement.?

Major decrease in the number of

Marginal decrease in the number of

Major decrease in the number of

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

Increase/decrease ; depends on the temperature

Molecular diffusivity of a liquid?

May increase or decrease with temperature

The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives?

High pressure drop and high hold up

Low pressure drop and high hold up

High pressure drop and low hold up

Low pressure drop and low hold up

High pressure drop and high hold up

Unsaturated air (with dry bulb and wet bulb temperatures being 45¬¨‚àûC and 25¬¨‚àûC respectively) is passed through a water spray chamber maintained at 23¬¨‚àûC. The air will be cooled and$

Humidified at constant wet bulb temperature

Humidified with wet bulb temperature decreasing

Humidified at constant wet bulb temperature

Humid volume is the total volume in m¬¨‚â• of 1 kg of$

Vapour laden gas at 1 atm. and gas temperature

Vapour laden gas at 1 atm. and room temperature

Gas plus its accompanying vapour at 1 atm. and room temperature

Gas plus its accompanying vapour at 1 atm. and gas temperature

Vapour laden gas at 1 atm. and gas temperature

The Schmidt number which is defined as, ≈í¬∫/≈ì√Ö D, is the ratio of the$

Thermal diffusivity to the mass diffusivity

Momentum diffusivity to the mass dif-fusivity

Thermal diffusivity to the mass diffusivity

Momentum diffusivity to the thermal diffusivity

The overall mass transfer co-efficient for the absorption of SO‚Äö√á√á in air with dilute NaOH solution can be increased substantially by$

Increasing the liquid film co-efficient

Increasing the gas film co-efficient

Increasing the liquid film co-efficient

Which of the following processes is not an example of adsorption applied to gaseous separations?

Recovery of valuable solvent vapors from dilute mixture with air and other gases

Dehumidification of air and gas

Removal of objectionable odour and impurities from industrial gases

Decolouration of yellow glycerene

The surface renewal frequency in Danckwerts model of mass transfer is given by (KL: mass transfer co-efficient)

‚Äö√ √∂(KL¬¨‚â§.DA)

Which of the following is an undesirable property in a tower packing?

Large weight of liquid retained

591 + Mcqs in Mass Transfer in Chemical Engineering Page 12 McqOptions

551.	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
Answer» C. Major decrease in the number of

Discussion

552.	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

553.	Molecular diffusivity of a liquid?
A.	Increases with temperature
B.	Decreases with temperature
C.	May increase or decrease with temperature
D.	Is independent of temperature
Answer» B. Decreases with temperature

Discussion

554.	The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature.?
A.	Dew point
B.	Wet bulb
C.	Dry bulb
D.	None of these
Answer» E.

Discussion

555.	Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty??
A.	Sieve plate column
B.	Bubble cap column
C.	Randomly packed column
D.	Wetted wall column
Answer» E.

Discussion

556.	The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives?
A.	Low pressure drop and high hold up
B.	High pressure drop and low hold up
C.	Low pressure drop and low hold up
D.	High pressure drop and high hold up
Answer» D. High pressure drop and high hold up

Discussion

557.	Plate efficiency in a distillation column is reduced due to the __________ of liquid.?
A.	Entrainment
B.	Foaming
C.	Weeping & dumping
D.	All of the above
Answer» E.

Discussion

558.	Heat sensitive materials with very high latent heat of vaporisation may be economically separated using?
A.	Liquid extraction
B.	Distillation
C.	Evaporation
D.	Absorption
Answer» B. Distillation

Discussion

559.	Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thiele's method??
A.	Partial condenser
B.	Total condenser
C.	Reboiler
D.	Both B and C
Answer» E.

Discussion

560.	Unsaturated air (with dry bulb and wet bulb temperatures being 45¬¨‚àûC and 25¬¨‚àûC respectively) is passed through a water spray chamber maintained at 23¬¨‚àûC. 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
Answer» B. Humidified at constant wet bulb temperature

Discussion

561.	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.m¬¨‚â§ and the solvent flow, rate is 400 moles of S/m¬¨‚â§. hr. The equilibrium data is represented by Y = 3X¬¨‚â§ , 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

562.	If moisture content of solid on dry basis is X, then the same on wet basis is
A.	X/(X + 1)
B.	X/(X - 1)
C.	(X + 1)/X
D.	(X - 1)/X
Answer» B. X/(X - 1)

Discussion

563.	Humid volume is the total volume in m¬¨‚â• 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
Answer» D. Vapour laden gas at 1 atm. and gas temperature

Discussion

564.	Which of the following is the most suitable for extraction in a system having very low density difference?
A.	Mixer-settler extractor
B.	Centrifugal extractor
C.	Pulsed extractor
D.	Packed extraction tower
Answer» C. Pulsed extractor

Discussion

565.	At equilibrium the concentration of water in vapour phase (C)in kg/m¬¨‚â• 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 100m¬¨‚â• 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

566.	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
Answer» D. None of these

Discussion

567.	Mass transfer co-efficient is directly proportional to DAB according to the __________ theory.
A.	Film
B.	Penetration
C.	Surface-renewal
D.	None of these
Answer» B. Penetration

Discussion

568.	Which of the following adsorbent is used to decolourise yellow glycerine?
A.	Silica gel
B.	Alumina
C.	Fuller
D.	Activated carbon
Answer» E.

Discussion

569.	Prandtl number for water at 20¬¨‚àûC is about$
A.	7
B.	70
C.	0.7
D.	150
Answer» B. 70

Discussion

570.	The Schmidt number which is defined as, ≈í¬∫/≈ì√Ö D, is the ratio of the$
A.	Momentum diffusivity to the mass dif-fusivity
B.	Thermal diffusivity to the mass diffusivity
C.	Momentum diffusivity to the thermal diffusivity
D.	None of these
Answer» B. Thermal diffusivity to the mass diffusivity

Discussion

571.	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
Answer» E.

Discussion

572.	The overall mass transfer co-efficient for the absorption of SO‚Äö√á√á in air with dilute NaOH solution can be increased substantially by$
A.	Increasing the gas film co-efficient
B.	Increasing the liquid film co-efficient
C.	Increasing the total pressure
D.	Decreasing the total pressure
Answer» B. Increasing the liquid film co-efficient

Discussion

573.	Which of the following equipments is not used in liquid-liquid extraction?
A.	Pachuka tank
B.	Agitated vessels
C.	Centrifugal extractors
D.	Packed towers
Answer» B. Agitated vessels

Discussion

574.	Which of the following processes is not an example of adsorption applied to gaseous separations?
A.	Recovery of valuable solvent vapors from dilute mixture with air and other gases
B.	Dehumidification of air and gas
C.	Removal of objectionable odour and impurities from industrial gases
D.	Decolouration of yellow glycerene
Answer» E.

Discussion

575.	Which of the following has the same dimension as mass diffusivity?
A.	Momentum flux
B.	Kinematic viscosity
C.	Thermal diffusivity
D.	Both A & B
Answer» E.

Discussion

576.	Which of the following quantities need not be fixed before starting the design of a co-current absorber?
A.	Heat gain or loss
B.	Flow rate of entering liquid
C.	Flow rate of gas
D.	None of these
Answer» C. Flow rate of gas

Discussion

577.	Which one of the following devices is not used for both the absorption as well as the liquid-liquid extraction processes?
A.	Packed towers
B.	Plate towers
C.	Spray towers
D.	Wetted wall columns
Answer» E.

Discussion

578.	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 of the above
Answer» B. Gas phase

Discussion

579.	Penetration theory states that the mass transfer co-coefficient is equal to (where, De is diffusivity and 't' is time)
A.	(De.t)1/2
B.	(De/t)1/2
C.	(4De/≈ì√Ñt)1/2
D.	(4De/t)
Answer» D. (4De/t)

Discussion

580.	What is the reflux ratio at total reflux?
A.	Zero
B.	Infinity
C.	Unity
D.	Data insufficient
Answer» C. Unity

Discussion

581.	The individual mass transfer co-efficients (moles/m¬¨‚â§ . s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?#
A.	Liquid side
B.	Gas side
C.	Interfacial
D.	Both liquid and gas side
Answer» C. Interfacial

Discussion

582.	At 750¬¨‚àûK 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

583.	Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty?
A.	Grid tray tower
B.	Perforated tray tower
C.	Wetted wall tower
D.	Bubble cap tower
Answer» E.

Discussion

584.	The surface renewal frequency in Danckwerts model of mass transfer is given by (KL: mass transfer co-efficient)
A.	‚Äö√ √∂(KL¬¨‚â§.DA)
B.	KL¬¨‚â§.DA
C.	KL¬¨‚â§/DA
D.	KL/DA¬¨‚â§
Answer» B. KL¬¨‚â§.DA

Discussion

585.	A mixture of 10% C‚Äö√á√úH‚Äö√á√ú vapour in air at 25¬¨‚àûC and 750 mm Hg has a dew point of 20¬¨‚àûC. Its dew point at 30¬¨‚àûC and 700 mm Hg will be around __________ ¬¨‚àûC.#
A.	21.7
B.	20
C.	27.3
D.	18.7
Answer» E.

Discussion

586.	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
Answer» E.

Discussion

587.	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
Answer» B. Drum dryer

Discussion

588.	Equilibrium moisture of a solid is equal to the total moisture minus free moisture. Which of the following substances will have maxi-mum equilibrium moisture?
A.	Anthracite coal
B.	Rag paper
C.	Bamboo
D.	Inorganic solids
Answer» D. Inorganic solids

Discussion

589.	Which of the following binary systems is an example of a maximum boiling azeotrope?
A.	Water-hydrochloric acid
B.	Acetone-carbon disulphide
C.	Water-ethyl alcohol
D.	N-heptane-n-octane
Answer» B. Acetone-carbon disulphide

Discussion

590.	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
Answer» E.

Discussion

591.	Polar organic compounds are normally used as separating agents for the azeotropic and extractive distillation. Which of the following is the most important factor to be considered for the choice of the separating agent for extractive distillation?
A.	Cost
B.	Availability
C.	Toxicity
D.	Selectivity
Answer» E.

Discussion

Explore topic-wise MCQs in Chemical Engineering.

For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement.?

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

Molecular diffusivity of a liquid?

The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature.?

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

The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives?

Plate efficiency in a distillation column is reduced due to the __________ of liquid.?

Heat sensitive materials with very high latent heat of vaporisation may be economically separated using?

Which of the following is considered equivalent to one theoretical stage in Mc-Cabe Thiele's method??

Unsaturated air (with dry bulb and wet bulb temperatures being 45¬¨‚àûC and 25¬¨‚àûC respectively) is passed through a water spray chamber maintained at 23¬¨‚àûC. The air will be cooled and$

If moisture content of solid on dry basis is X, then the same on wet basis is

Humid volume is the total volume in m¬¨‚â• of 1 kg of$

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

Which of the following remains constant during evaporative cooling process with recirculated water supply?

Mass transfer co-efficient is directly proportional to DAB according to the __________ theory.

Which of the following adsorbent is used to decolourise yellow glycerine?

Prandtl number for water at 20¬¨‚àûC is about$

The Schmidt number which is defined as, ≈í¬∫/≈ì√Ö D, is the ratio of the$

Which of the following equipments is not used for gas dispersion?

The overall mass transfer co-efficient for the absorption of SO‚Äö√á√á in air with dilute NaOH solution can be increased substantially by$

Which of the following equipments is not used in liquid-liquid extraction?

Which of the following processes is not an example of adsorption applied to gaseous separations?

Which of the following has the same dimension as mass diffusivity?

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

Which one of the following devices is not used for both the absorption as well as the liquid-liquid extraction processes?

In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of __________ is zero.

Penetration theory states that the mass transfer co-coefficient is equal to (where, De is diffusivity and 't' is time)

What is the reflux ratio at total reflux?

The individual mass transfer co-efficients (moles/m¬¨‚â§ . s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?#

At 750¬¨‚àûK and 1 atm, the approximate value of Schmidt number for air is#

Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty?

The surface renewal frequency in Danckwerts model of mass transfer is given by (KL: mass transfer co-efficient)

A mixture of 10% C‚Äö√á√úH‚Äö√á√ú vapour in air at 25¬¨‚àûC and 750 mm Hg has a dew point of 20¬¨‚àûC. Its dew point at 30¬¨‚àûC and 700 mm Hg will be around __________ ¬¨‚àûC.#

Which of the following is an undesirable characteristic for the solvent used in gas absorption?

A slurry is to be dried to produce flaky solid. Which dryer would you recommend?

Equilibrium moisture of a solid is equal to the total moisture minus free moisture. Which of the following substances will have maxi-mum equilibrium moisture?

Which of the following binary systems is an example of a maximum boiling azeotrope?

Which of the following is an undesirable property in a tower packing?

Polar organic compounds are normally used as separating agents for the azeotropic and extractive distillation. Which of the following is the most important factor to be considered for the choice of the separating agent for extractive distillation?