*/*_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,?

As the acetone concentration increases, the solubility curves approach each other

Both the phases become identical at a particular common point on both the solubility curves called the plait point

The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption termina

%_The rate of mass transfer is not dependent upon the_%

Degree of dispersion of one fluid in the other

Interfacial surface exposed between the phases

%_For water-ethanol system, the minimum reflux ratio_%

Is computed from the intercept of the operating line

Is computed from the slope of the upper operating line that is tangent to the equilibrium curve

Is computed from the intercept of the operating line

%_In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is_%

Equal to the heat of formation of surface compound

Called integral heat of adsorption

%_Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when_%

Extracting solvent is cheaply & abundantly available

One of the liquid components is heat sensitive

Viscosity of liquid components is very high

One of the liquid components has very high affinity towards the solvent

%_The Knudsen diffusivity is dependent on the_%

Pore radius of the catalyst only

Molecular velocity and por radius of the catalyst

%_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,_%

As the acetone concentration increases, the solubility curves approach each other

Both the phases become identical at a particular common point on both the solubility curves called the plait point

The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption termina

%_The cooling effect in a cooling tower can be speeded up by_%

Increasing the air velocity and area of exposed wet surface

Reducing the barometric pressure

Reducing the humidity of the air

%_Stacked packing compared to dumped packing_%

Provides poorer contact between the fluids

%_In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapour, because_%

Saturated steam is used for steam distillation

Mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition

Saturated steam is used for steam distillation

%_As per Gilliland's equation, the diffusivity is_%

Directly proportional to 'T1.5'

Dependent on the molecular volume & molecular weight of components

%_Chemisorption compared to physical absorption has_%

Lower capacity of the solvent for the solute gas

Increased utilisation of stagnant zones of the liquid phase

%_Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in_%

Degree of ideality of the solution

%_A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process?_%

Relative humidity of outlet air

%_In most of the vacuum crystalliser, vacuum is generally produced by means of a_%

Steam jet ejector with a barometric condenser

_ Pick out the wrong statement pertaining to the rotary dryer.$?

Recommended peripherial speed of a rotary drier is in the range of 10 to 30 metres/minute

Flights (located in the inside shell of rotary dryer) lift the material being dried and shower it down through the current of hot air/gases. It extends from the wall to a distance which is about 8-12%

Hold up of a rotary drier is defined as the fraction of the dryer volume occupied by the solid at any instant. The best performance for rotary drier is obtained, when the hold up is in the range of 0.

Rotary dryer is suitable for drying sticky material

Recommended peripherial speed of a rotary drier is in the range of 10 to 30 metres/minute

591 + Mcqs in Mass Transfer in Chemical Engineering Page 5 McqOptions

201.	/_Water entrained by circulating air in cooling towers is termed as?
A.	Drift
B.	Blow down
C.	Vapor load
D.	None of these
Answer» B. Blow down

202.	/_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,?
A.	As the acetone concentration increases, the solubility curves approach each other
B.	Both the phases become identical at a particular common point on both the solubility curves called the plait point
C.	The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption termina
D.	All of the above
Answer» E.

203.	%_The rate of mass transfer is not dependent upon the_%
A.	Degree of dispersion of one fluid in the other
B.	Interfacial surface exposed between the phases
C.	Both A & B
D.	None of these
Answer» E.

204.	%_When both the fluids flow concurrently in an absorber, the slope of the operating line is_%
A.	- ve
B.	+ ve
C.	1
D.	-1
Answer» B. + ve

205.	%_For water-ethanol system, the minimum reflux ratio_%
A.	Is computed from the slope of the upper operating line that is tangent to the equilibrium curve
B.	Is computed from the intercept of the operating line
C.	Cannot be computed
D.	Is the optimum reflux ratio
Answer» B. Is computed from the intercept of the operating line

206.	%_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
Answer» D. None of these

207.	%___________ is the separation technique used for desalination of sea water._%
A.	Thermal diffusion
B.	Reverse osmosis
C.	Adsorption
D.	Absorption
Answer» C. Adsorption

208.	%_Wetted wall tower experiment determines the_%
A.	Molal diffusivity
B.	Volumetric co-efficient
C.	Mass transfer co-efficient
D.	None of these
Answer» D. None of these

209.	%_Which of the following mixtures does not form an azeotrope at atmosheric pressure?_%
A.	Water-alcohol
B.	Methyl alcohol-acetone
C.	Butyl acetate-water
D.	None of these
Answer» E.

210.	%_Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature)_%
A.	Log P vs . T
B.	Log P vs. log T
C.	T vs . P
D.	P vs . log T
Answer» B. Log P vs. log T

211.	%_Desirable value of absorption factor in an absorber is_%
A.	1
B.	< 1
C.	> 1
D.	0.5
Answer» D. 0.5

212.	%_For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be_%
A.	1
B.	0
C.	2
D.	3
Answer» B. 0

213.	%_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
Answer» D. 0.6

223.	%_Pore size of the molecular seive 5A is __________ mm._%
A.	5
B.	0.5
C.	0.05
D.	50
Answer» C. 0.05

224.	%_In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be_%
A.	At ground level
B.	2 metres above the ground
C.	5 metres above ground
D.	10 metres above ground
Answer» B. 2 metres above the ground

214.	%_In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is_%
A.	Equal to the heat of formation of surface compound
B.	Equal to the heat of wetting
C.	Zero
D.	Called integral heat of adsorption
Answer» C. Zero

215.	%_The binary diffusivity in gases does not depend upon the_%
A.	Pressure
B.	Temperature
C.	Nature of the components
D.	None of these
Answer» E.

216.	%_Diameter to height ratio for a rashig ring is_%
A.	1
B.	0.5
C.	2
D.	8
Answer» B. 0.5

217.	%_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
Answer» E.

218.	%_The Knudsen diffusivity is dependent on the_%
A.	Molecular velocity only
B.	Pore radius of the catalyst only
C.	Molecular mean free path only
D.	Molecular velocity and por radius of the catalyst
Answer» E.

219.	%_Water entrained by circulating air in cooling towers is termed as_%
A.	Drift
B.	Blow down
C.	Vapor load
D.	None of these
Answer» B. Blow down

220.	%_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,_%
A.	As the acetone concentration increases, the solubility curves approach each other
B.	Both the phases become identical at a particular common point on both the solubility curves called the plait point
C.	The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption termina
D.	All of the above
Answer» E.

221.	%_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 of the above
Answer» E.

222.	%_Stacked packing compared to dumped packing_%
A.	Provides poorer contact between the fluids
B.	Gives lower pressure drop
C.	Both A & B
D.	Gives higher pressure drop
Answer» D. Gives higher pressure drop

225.	%_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
Answer» C. Both A & B

Explore topic-wise MCQs in Chemical Engineering.

*/*_Water entrained by circulating air in cooling towers is termed as?

*/*_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,?

%_The rate of mass transfer is not dependent upon the_%

%_When both the fluids flow concurrently in an absorber, the slope of the operating line is_%

%_For water-ethanol system, the minimum reflux ratio_%

%_The percentage humidity is less than the relative humidity only at __________ percent humidity._%

%___________ is the separation technique used for desalination of sea water._%

%_Wetted wall tower experiment determines the_%

%_Which of the following mixtures does not form an azeotrope at atmosheric pressure?_%

%_Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature)_%

%_Desirable value of absorption factor in an absorber is_%

%_For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be_%

%_In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of_%

%_In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is_%

%_The binary diffusivity in gases does not depend upon the_%

%_Diameter to height ratio for a rashig ring is_%

%_Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when_%

%_The Knudsen diffusivity is dependent on the_%

%_Water entrained by circulating air in cooling towers is termed as_%

%_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,_%

%_The cooling effect in a cooling tower can be speeded up by_%

%_Stacked packing compared to dumped packing_%

%_Pore size of the molecular seive 5A is __________ mm._%

%_In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be_%

%_In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase._%

%_In triangular co-ordinates, the ternery composition point falls __________ of the triangle._%

%_Large scale drying of wheat is done in a __________ dryer._%

%_For which of the following unit operations, Lewis number is of significance?_%

%_In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapour, because_%

%_Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate._%

%_As per Gilliland's equation, the diffusivity is_%

%_The operating line for an absorber is curved, when plotted in terms of_%

%_What is the degree of freedom of an absorption process in which only one component is transferred between phases?_%

%_Chemisorption compared to physical absorption has_%

%_According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity)_%

%_The equipment used in the extraction of highly corrosive radio active liquids is_%

%_Reverse osmosis is also called_%

%_The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is_%

%_In the absorption of ammonia in water, the main resistance to absorption is by the __________ phase._%

%_Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in_%

%_Rate of adsorption increases as the_%

%_Which of the following is not a batch drier?_%

%_Which of the following is the most commonly used leaching solvent in vegetable oil industry?_%

%_A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process?_%

%_In most of the vacuum crystalliser, vacuum is generally produced by means of a_%

%_Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1¬¨‚àûF is called the_%

_ For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same.$?

_ Pick out the wrong statement pertaining to the rotary dryer.$?

_ In liquid-liquid extraction, the number of phases at plait point is$?

/_Water entrained by circulating air in cooling towers is termed as?

/_When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30¬¨‚àûC, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,?

226.	%_In triangular co-ordinates, the ternery composition point falls __________ of the triangle._%
A.	In the corners
B.	Inside
C.	On the sides
D.	None of these
Answer» C. On the sides

227.	%_Large scale drying of wheat is done in a __________ dryer._%
A.	Fluidised bed
B.	Spouted bed
C.	Tray
D.	Vacuum rotary
Answer» C. Tray

228.	%_For which of the following unit operations, Lewis number is of significance?_%
A.	Adsorption
B.	Binary distillation
C.	Gas absorption
D.	Humidification
Answer» E.

229.	%_In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapour, because_%
A.	Temperature is less
B.	Total pressure is less
C.	Mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition
D.	Saturated steam is used for steam distillation
Answer» D. Saturated steam is used for steam distillation

230.	%_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
Answer» C. Does not affect

231.	%_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 of the above
Answer» E.

232.	%_The operating line for an absorber is curved, when plotted in terms of_%
A.	Mole fractions
B.	Mole ratios
C.	Partial pressure
D.	Mass fractions
Answer» D. Mass fractions

233.	%_What is the degree of freedom of an absorption process in which only one component is transferred between phases?_%
A.	3
B.	2
C.	4
D.	1
Answer» B. 2

234.	%_Chemisorption compared to physical absorption has_%
A.	Lower adsorption rate
B.	Lower capacity of the solvent for the solute gas
C.	Increased utilisation of stagnant zones of the liquid phase
D.	None of these
Answer» D. None of these

235.	%_According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity)_%
A.	D
B.	D2
C.	D0.5
D.	1/D
Answer» B. D2