_ Flash distillation is suitable for separating the constituents of a binary system, which$?

Form constant boiling azeotrope

_ Flash distillation is suitable for the separation of components$?

Which form minimum boiling azeotrope

Having very close boiling points

Which form maximum boiling azeotrope

Having very wide boiling points

Which form minimum boiling azeotrope

_ During the constant rate period of drying of a solid,$?

Increased air humidity decreases the rate of drying

Increasing the air temperature decreases the drying rate

Surface evaporation of unbound moisture occurs

_ Stage efficiency in a leaching process depends on the$?

Vapour pressure of the solution

Time of contact between the solid and the solution

Rate of diffusion of the solute through the solid and into the liquid

Vapour pressure of the solution

_ Leaching of coffee from coffee beans is done by$?

Dilute H‚Äö√á√áSO‚Äö√á√ë (hot)

_ Berl saddle made of carbon cannot be used for$?

H‚Äö√á√áSO‚Äö√á√ë

_ Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10‚Äö√Ö¬™¬¨‚â• kg mole/m¬¨‚â§.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m¬¨‚â§ .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is$?

5.6 x 10‚Äö√Ö¬™¬¨‚â•

5.6 x 10‚Äö√Ö¬™‚Äö√Ö¬•

8.5 x 10‚Äö√Ö¬™‚Äö√Ö¬•

5.6 x 10‚Äö√Ö¬™¬¨‚â•

8.5 x 10‚Äö√Ö¬™¬¨‚â•

_ Air initially at 101. 3 kPa and 40¬¨‚àûC and with a relative humidity of 50%, is cooled at constant pressure to 30¬¨‚àûC. The cooled air has a$?

Higher absolute (specific) humidity

_ Which of the following processes is followed by unsaturated air (with dry bulb temperature 12¬¨‚àûC and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40¬¨‚àûC?$?

Both heating and humidification

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

Partial pressure of vapour in the mixture

_ When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption.$?

Dependent on the system; can be either lower or higher than

_ 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

_ In a counter-current liquid extractor$?

Liquid's flow rate depends upon the temperature and pressure

Both liquids flow at fixed rate

Both liquids can have any desired flow rate

Only one of the liquids may be pumped at any desired rate

Liquid's flow rate depends upon the temperature and pressure

_ Pick out the wrong statement pertaining to leaching.$?

Door classifier can be used for leaching of coarse solids

Fine solids can not be leached in a Pachuka tank

Door classifier can be used for leaching of coarse solids

Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor

Very high temperature is not needed for the leaching of sugar beet

_ In liquid extraction, if the selectivity is unity, then$?

Amount of solvent required will be minimum

Separation of the constituents is the most effective

Amount of solvent required will be minimum

Solvent flow rate should be very low

_ Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of$?

Momentum diffusivity to thermal diffusivity

Mass diffusivity to momentum diffusivity

Thermal diffusivity to mass diffusivity

Momentum diffusivity to thermal diffusivity

591 + Mcqs in Mass Transfer in Chemical Engineering Page 6 McqOptions

251.	_ Flash distillation is suitable for separating the constituents of a binary system, which$?
A.	Form minimum boiling azeotrope
B.	Have very wide boiling points
C.	Have very close boiling points
D.	Form constant boiling azeotrope
Answer» C. Have very close boiling points

Discussion

252.	_ Rotary dryers cannot handle __________ materials.$?
A.	Free flowing
B.	Dry
C.	Sticky
D.	Grannular
Answer» D. Grannular

Discussion

253.	_ Flash distillation is suitable for the separation of components$?
A.	Having very close boiling points
B.	Which form maximum boiling azeotrope
C.	Having very wide boiling points
D.	Which form minimum boiling azeotrope
Answer» D. Which form minimum boiling azeotrope

Discussion

254.	_ If the path of liquid across the plate is very long as in case of large diameter tower, Murphree efficiency can be __________ percent.$?
A.	100
B.	> 100
C.	< 100
D.	None of these
Answer» C. < 100

Discussion

255.	_ Total reflux in a distillation operation requires minimum$?
A.	Reboiler load
B.	Number of plates
C.	Condenser load
D.	All of the above
Answer» C. Condenser load

Discussion

256.	_ The suitable evaporator for concentration of foaming liquids is a __________ evaporator.$?
A.	Long tube
B.	Short tube
C.	Vacuum
D.	Falling film
Answer» B. Short tube

Discussion

257.	_ Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture.$?
A.	Unbound
B.	Critical
C.	Free
D.	Bound
Answer» B. Critical

Discussion

258.	_ The reciprocal of stripping factor is termed as$?
A.	Selectivity index
B.	Relative volatility
C.	Absorption factor
D.	Murphree efficiency
Answer» D. Murphree efficiency

Discussion

259.	_ The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m¬¨‚â§/m¬¨‚â•)$?
A.	500
B.	1200
C.	900
D.	800
Answer» B. 1200

Discussion

260.	_ In gas-liquid contact operation, the number of ideal stages, N = (xa - xb)/(xb - x*b) . This is true when the stripping factor 'S' is$?
A.	S > 1
B.	S < 1
C.	S = 1
D.	S = ‚Äö√ √ª
Answer» B. S < 1

Discussion

261.	_ Sand is dried in foundaries in a___drier.$?
A.	Rotary
B.	Fluidisedbed
C.	Vacuum
D.	Spray
Answer» C. Vacuum

Discussion

262.	_ Hypersorption refers to a __________ process.$?
A.	Fixed bed absorption
B.	Moving bed absorption
C.	Fixed bed adsorption
D.	Moving bed adsorption
Answer» E.

Discussion

263.	_ A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is$?
A.	0.54
B.	1.04
C.	1.24
D.	1.94
Answer» D. 1.94

Discussion

264.	_ During the constant rate period of drying of a solid,$?
A.	Increased air humidity decreases the rate of drying
B.	Increasing the air temperature decreases the drying rate
C.	Surface evaporation of unbound moisture occurs
D.	None of these
Answer» D. None of these

Discussion

265.	_ 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 & B
D.	Vapour pressure of the solution
Answer» D. Vapour pressure of the solution

Discussion

266.	_ Leaching of coffee from coffee beans is done by$?
A.	Hot water
B.	Hexane
C.	Lime water
D.	Dilute H‚Äö√á√áSO‚Äö√á√ë (hot)
Answer» B. Hexane

Discussion

267.	_ Berl saddle made of carbon cannot be used for$?
A.	Alkalis
B.	SO‚Äö√á√á
C.	H‚Äö√á√áSO‚Äö√á√ë
D.	Oxidising atmosphere
Answer» E.

Discussion

268.	_ Packed column distillation is limited to the column __________ metres.$?
A.	Height < 6
B.	Diameter < 0.6
C.	Both A & B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

269.	_ Which of the following assumes constant molal vaporisation and overflow?$?
A.	McCabe-Thiele method
B.	Ponchan-Savarit method
C.	Enthalpy concentration method
D.	Plate absorption column
Answer» B. Ponchan-Savarit method

Discussion

270.	_ Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10‚Äö√Ö¬™¬¨‚â• kg mole/m¬¨‚â§.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m¬¨‚â§ .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is$?
A.	5.6 x 10‚Äö√Ö¬™‚Äö√Ö¬•
B.	8.5 x 10‚Äö√Ö¬™‚Äö√Ö¬•
C.	5.6 x 10‚Äö√Ö¬™¬¨‚â•
D.	8.5 x 10‚Äö√Ö¬™¬¨‚â•
Answer» C. 5.6 x 10‚Äö√Ö¬™¬¨‚â•

Discussion

271.	_ 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
Answer» C. Same as

Discussion

272.	_ Operating velocity in a packed tower is usually __________ the flooding velocity.$?
A.	Half
B.	Twice
C.	Equal to
D.	More than
Answer» B. Twice

Discussion

273.	_ The relative volatility of a binary mixture at constant temperature __________ the total pressure.$?
A.	Decreases with increase in
B.	Increases with increase in
C.	Is independent of
D.	None of these
Answer» B. Increases with increase in

Discussion

274.	_ Air initially at 101. 3 kPa and 40¬¨‚àûC and with a relative humidity of 50%, is cooled at constant pressure to 30¬¨‚àûC. The cooled air has a$?
A.	Higher dew point
B.	Higher absolute (specific) humidity
C.	Higher relative humidity
D.	Higher wet bulb temperature
Answer» D. Higher wet bulb temperature

Discussion

275.	_ The most efficient cooling tower out of the following is$?
A.	Induced draft
B.	Forced draft
C.	Natural draft
D.	Atmospheric
Answer» B. Forced draft

Discussion

276.	_ Which of the following processes is followed by unsaturated air (with dry bulb temperature 12¬¨‚àûC and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40¬¨‚àûC?$?
A.	Humidification only
B.	Heating only
C.	Both heating and humidification
D.	Evaporative cooling
Answer» D. Evaporative cooling

Discussion

277.	_ 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

278.	_ If the specific heats of a gas and a vapor are 0.2KJ/Kg.¬¨‚àûK and 1.5 KJ/Kg.¬¨‚àûK respectively, and the humidity is 0.01; the humid heat in KJ/¬¨‚àûKg. is$?
A.	0.31
B.	0.107
C.	0.017
D.	0.215
Answer» E.

Discussion

279.	_ When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption.$?
A.	Always lower than
B.	Always higher than
C.	Same as
D.	Dependent on the system; can be either lower or higher than
Answer» B. Always higher than

Discussion

280.	_ 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

281.	_ __________ is used as an 'entrainer' for the separation of acetic acid-water mixture by distillation.$?
A.	Furfural
B.	Benzol
C.	Butyl acetate
D.	Hexane
Answer» D. Hexane

Discussion

282.	_ Unit operation involved in the prilling of urea is$?
A.	Evaporation
B.	Drying
C.	Crystallisation
D.	Both B and C
Answer» E.

Discussion

283.	_ Refractory bricks are usually dried in a __________ dryer.$?
A.	Tray
B.	Tunnel
C.	Conveyor
D.	Festoon
Answer» C. Conveyor

Discussion

284.	_ An azeotropic mixture is a __________ mixture.$?
A.	Binary
B.	Ternary
C.	Constant boiling point
D.	None of these
Answer» D. None of these

Discussion

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

Discussion

286.	_ Raoult's law is applicable to the$?
A.	Ideal solutions
B.	Real solutions
C.	Mixture of water and alcohol
D.	Non-ideal gases
Answer» B. Real solutions

Discussion

287.	_ 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

288.	_ During sensible cooling process$?
A.	Relative humidity decreases
B.	Relative humidity increases
C.	Wet bulb temperature decreases
D.	Both B and C
Answer» E.

Discussion

289.	_ In a counter-current liquid extractor$?
A.	Both liquids flow at fixed rate
B.	Both liquids can have any desired flow rate
C.	Only one of the liquids may be pumped at any desired rate
D.	Liquid's flow rate depends upon the temperature and pressure
Answer» D. Liquid's flow rate depends upon the temperature and pressure

Discussion

290.	_ The fixed cost of a distillation column at minimum reflux ratio is$?
A.	Minimum
B.	Infinite
C.	Optimum
D.	None of these
Answer» C. Optimum

Discussion

291.	_ Pick out the wrong statement pertaining to leaching.$?
A.	Fine solids can not be leached in a Pachuka tank
B.	Door classifier can be used for leaching of coarse solids
C.	Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor
D.	Very high temperature is not needed for the leaching of sugar beet
Answer» B. Door classifier can be used for leaching of coarse solids

Discussion

292.	_ (NRe . NSc) is termed in mass transfer operation as the __________ number.$?
A.	Stanton
B.	Sherwood
C.	Peclet
D.	None of these
Answer» D. None of these

Discussion

293.	_ In liquid extraction, if the selectivity is unity, then$?
A.	Separation of the constituents is the most effective
B.	No separation will occur
C.	Amount of solvent required will be minimum
D.	Solvent flow rate should be very low
Answer» C. Amount of solvent required will be minimum

Discussion

294.	_ Pick out the correct relationship. (where, Ri = internal reflux ratio Ro = external reflux ratio. )$?
A.	(1 + Ro) = Ro/Ri
B.	(1 - Ro) = Ro/Ri
C.	(1 + Ri) = Ro/Ri
D.	(1 - Ri) = Ro/Ri
Answer» B. (1 - Ro) = Ro/Ri

Discussion

295.	_ With increase in temperature, the mutual solubility of two liquids$?
A.	Increases
B.	Decreases
C.	Remains unchanged
D.	Decreases exponentially
Answer» B. Decreases

Discussion

296.	_ Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of$?
A.	Mass diffusivity to momentum diffusivity
B.	Thermal diffusivity to mass diffusivity
C.	Momentum diffusivity to thermal diffusivity
D.	None of these
Answer» C. Momentum diffusivity to thermal diffusivity

Discussion

297.	_ During bottling of cold drinks (e.g. Pepsi), the main resistance to mass transfer for the absorption of carbon dioxide in water lies in the$?
A.	Gas film
B.	Liquid film
C.	Liquid-gas interface
D.	None of these
Answer» C. Liquid-gas interface

Discussion

298.	_ The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is$?
A.	0
B.	‚Äö√ √ª
C.	-ve
D.	+ve
Answer» D. +ve

Discussion

299.	_ Stefan's law describes the mass transfer by$?
A.	Diffusion
B.	Bulk flow
C.	Both A & B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

300.	_ The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called$?
A.	Decoction
B.	Percolation
C.	Elutriation or elution
D.	None of these
Answer» D. None of these

Discussion

Explore topic-wise MCQs in Chemical Engineering.

_ Flash distillation is suitable for separating the constituents of a binary system, which$?

_ Rotary dryers cannot handle __________ materials.$?

_ Flash distillation is suitable for the separation of components$?

_ If the path of liquid across the plate is very long as in case of large diameter tower, Murphree efficiency can be __________ percent.$?

_ Total reflux in a distillation operation requires minimum$?

_ The suitable evaporator for concentration of foaming liquids is a __________ evaporator.$?

_ Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture.$?

_ The reciprocal of stripping factor is termed as$?

_ The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m¬¨‚â§/m¬¨‚â•)$?

_ In gas-liquid contact operation, the number of ideal stages, N = (xa - xb)/(xb - x*b) . This is true when the stripping factor 'S' is$?

_ Sand is dried in foundaries in a___drier.$?

_ Hypersorption refers to a __________ process.$?

_ A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is$?

_ During the constant rate period of drying of a solid,$?

_ Stage efficiency in a leaching process depends on the$?

_ Leaching of coffee from coffee beans is done by$?

_ Berl saddle made of carbon cannot be used for$?

_ Packed column distillation is limited to the column __________ metres.$?

_ Which of the following assumes constant molal vaporisation and overflow?$?

_ 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.$?

_ Operating velocity in a packed tower is usually __________ the flooding velocity.$?

_ The relative volatility of a binary mixture at constant temperature __________ the total pressure.$?

_ Air initially at 101. 3 kPa and 40¬¨‚àûC and with a relative humidity of 50%, is cooled at constant pressure to 30¬¨‚àûC. The cooled air has a$?

_ The most efficient cooling tower out of the following is$?

_ Which of the following processes is followed by unsaturated air (with dry bulb temperature 12¬¨‚àûC and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40¬¨‚àûC?$?

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

_ If the specific heats of a gas and a vapor are 0.2KJ/Kg.¬¨‚àûK and 1.5 KJ/Kg.¬¨‚àûK respectively, and the humidity is 0.01; the humid heat in KJ/¬¨‚àûKg. is$?

_ When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption.$?

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

_ __________ is used as an 'entrainer' for the separation of acetic acid-water mixture by distillation.$?

_ Unit operation involved in the prilling of urea is$?

_ Refractory bricks are usually dried in a __________ dryer.$?

_ An azeotropic mixture is a __________ mixture.$?

_ Which of the following equipments is not used for liquid dispersion?$?

_ Raoult's law is applicable to the$?

_ Components, having widely different boiling point in a binary mixture, can be separated using __________ distillation.$?

_ During sensible cooling process$?

_ In a counter-current liquid extractor$?

_ The fixed cost of a distillation column at minimum reflux ratio is$?

_ Pick out the wrong statement pertaining to leaching.$?

_ (NRe . NSc) is termed in mass transfer operation as the __________ number.$?

_ In liquid extraction, if the selectivity is unity, then$?

_ Pick out the correct relationship. (where, Ri = internal reflux ratio Ro = external reflux ratio. )$?

_ With increase in temperature, the mutual solubility of two liquids$?

_ Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of$?

_ During bottling of cold drinks (e.g. Pepsi), the main resistance to mass transfer for the absorption of carbon dioxide in water lies in the$?

_ The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is$?

_ Stefan's law describes the mass transfer by$?

_ The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called$?