Latest Chemical Engineering MCQs – Competitive Mass Transfer MCQs
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Latest Chemical Engineering MCQs
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Latest Mass Transfer Mcqs
The most occurred mcqs of Mass Transfer in past papers. Past papers of Mass Transfer Mcqs. Past papers of Mass Transfer Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Mass Transfer Mcqs. The Important series of Mass Transfer Mcqs are given below:
The relation, Sc = Pr = 1, is valid, when the mechanism of ______________ transfer is same?
A. Heat and mass
B. Heat and momentum
C. Mass and momentum
D. Heat, momentum and mass
McCabe-Thiele method________________?
A. Uses molal units for material and energy balance
B. Can use any type of units
C. Uses weight fractions to express liquid and vapour composition
D. Is more accurate than Ponchon-Savarit method
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
If the specific heats of a gas and a vapor are 0.2KJ/Kg.°K and 1.5 KJ/Kg.°K respectively, and the humidity is 0.01; the humid heat in KJ/°Kg. is________________?
A. 0.107
B. 0.31
C. 0.017
D. 0.215
In case of ______________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated?
A. Azeotropic
B. Molecular
C. Extractive
D. Flash
Moisture contained by a substance in excess of the equilibrium moisture is called the _______________ moisture?
A. Critical
B. Free
C. Unbound
D. Bound
Hypersorption refers to a ________________ process?
A. Moving bed absorption
B. Fixed bed absorption
C. Fixed bed adsorption
D. Moving bed adsorption
In case of liquids, the binary diffusivity is proportional to (where, T = temperature) _____________________?
A. T
B. T2
C. √T
D. 1/T
The relative saturation of an unsaturated mixture of gas and vapor is independent of the___________________?
A. Temperature of the mixture
B. Nature of the vapor
C. Composition of the mixture
D. None of these
Advantage of continuous drying over batch drying is that the_____________________?
A. Equipment size required is smaller
B. Product with more uniform moisture content is produced
C. Drying cost per unit weight of dried product is less
D. All A , B. & C.
An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is__________________?
A. 0.079
B. 0.048
C. 0.122
D. 0.152
For an absorber, both equilibrium and operating line will be straight for _______________________?
A. Dilute solution and non-isothermal operation
B. Concentrated solution and non-isothermal operation
C. Dilute solution and isothermal operation
D. Concentrated solution and isothermal operation
Penetration model (theory) for mass transfer was enunciated by _____________________?
A. Toor and Marcello
B. Danckwerts
C. Higbie
D. Kissinevskii
Milk is dried usually in a __________________ dryer?
A. Tray
B. Spray
C. Freeze
D. Rotary
Unit of molal diffusivity is____________________?
A. gm moles/cm2 . sec
B. cm2/sec gm . mole
C. gm moles/cm. sec
D. gm moles/cm2. sec
In case of non-ideal gases and liquids, the molal diffusivity ________________?
A. Varies directly as the pressure
B. Varies inversely as the pressure
C. Is independent of pressure
D. Is equal to the volumetric diffusivity
Which of the following is a suitable absorbent for removal of H2S from natural gas ?
A. Dilute
B. Monoethanolamine (MEA)
C. Vetrocoke solution
D. Hot water
Fertilizer Technology Mcqs
Humid volume is the total volume in m3 of 1 kg of _____________________?
A. Gas plus its accompanying vapour at 1 atm. and room temperature
B. Vapour laden gas 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
Components, having widely different boiling point in a binary mixture, can be separated using ________________ distillation?
A. Extractive
B. Molecular
C. Steam
D. Simple
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. Dehumidified
C. Humidified at constant wet bulb temperature
D. None of these
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. Rag paper
B. Anthracite coal
C. Bamboo
D. Inorganic solids
At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbent __________________?
A. Remains unchanged
B. Decreases
C. Increases
D. Increases exponentially
HETP is numerically equal to HTU, only when the operating line ______________________?
A. Lies above the equilibrium line
B. Lies below the equilibrium line
C. And equilibrium lines are parallel
D. Is far from the equilibrium line
Drift in a cooling tower is ___________________?
A. The water entrained by the circulating air
B. Desirable
C. Dependent on the water lost by evaporation
D. All A., B. & C.
Gaseous diffusivity at atmospheric pressure is of the order of _____________________ cm2/second?
A. 1
B. 5 to 10
C. 1 to 5
D. > 10
_______________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower?
A. Stanton
B. Sherwood
C. Lewis
D. Peclet
If Rm is the minimum reflux ratio, the optimum reflux ratio may be around _________________ Rm ?
A. 1.2 to 1.5
B. 3 to 4
C. 2.5 to 3
D. 5
Surface renewal model of mass transfer was enunciated by___________________?
A. Fick
B. Toor and Marcello
C. Danckwerts
D. Stefan
Which of the following adsorbent is used to decolourise yellow glycerine ?
A. Silica gel
B. Fuller’s earth
C. Alumina
D. Activated carbon
Binary distillation involves the mass transfer by ______________________ at the gas-liquid interface?
A. Unidirectional diffusion from gas to liquid phase
B. Unidirectional diffusion from liquid to gas phase
C. Either A. or B.
D. A counter diffusion at an almost equal molar rate
Sand is dried in foundries in a ______________________drier?
A. Vacuum
B. Fluidised bed
C. Rotary
D. Spray
Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are ?
A. 8
B. 4
C. 9
D. 10
Fuels And Combustion Mcqs
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. No amount of C is transferred to B
D. Less than 1 kg of C is transferred to B
Azeotropism for ethyl alcohol-water system disappears by_____________________?
A. Increasing pressure
B. Decreasing pressure
C. Increasing temperature
D. No means
The falling rate period in the drying of a solid is characterised by__________________?
A. Decreasing temperatures
B. Increasing temperatures both on the surface and within the solid
C. Increase in rate of drying
D. None of these
Schmidt number and Lewis number for pure air at atmospheric conditions are respectively__________________?
A. < 1 and ≈ 1
B. > 1 and ≈ 1
C. 1 and 0
D. 0 and ≈ 1
Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the_________________?
A. Mass transfer co-efficient
B. Kinematic viscosity
C. Thermal diffusivity
D. Volumetric diffusivity
Which of the following equipments is not used for liquid dispersion ?
A. Packed towers
B. Wetted wall towers
C. Venturi scrubbers
D. Agitated vessels
The solvent used in liquid-liquid extraction should have _______________ less than one?
A. Distribution co-efficient
B. Selectivity
C. Both A. and B.
D. Neither A. nor B.
Out of the following gas-liquid contacting devices, for a given set of operating conditions, gas pressure drop is the least in ______________ tower?
A. Wetted wall
B. Perforated tray
C. Bubble cap
D. Packed
Ordinary diffusion process is also called ______________ diffusion?
A. Thermal
B. Pressure
C. Concentration
D. Forced
Decoction refers to the use of solvent________________?
A. In its vapor form
B. At its boiling point
C. At ambient temperature
D. None of these
The binary diffusivity in gases and liquids vary respectively as_________________?
A. T3/2 and T
B. √T and T3/2 T
C. and T3/2
D. T3/2 and √T
Cox chart is useful in the design of___________________?
A. Distillation column
B. Dryer
C. Evaporator
D. Crystalliser
Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the ________________ number?
A. Sherwood
B. Peclet
C. Schmidt
D. Stanton
Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of__________________?
A. Momentum diffusivity to thermal diffusivity
B. Thermal diffusivity to mass diffusivity
C. Mass diffusivity to momentum diffusivity
D. None of these
Agitator is provided in a crystalliser for____________________?
A. Formation of nuclei
B. Avoiding deposition on cooler surfaces
C. Crystal growth
D. All A., B. and C.
Adsorption is a unit operation which generally involves _______________ systems?
A. Gas-solid
B. Liquid-solid
C. Fluid-solid
D. Solid-solid
Molarity is defined as the number of gm moles of solute per ________________ of solvent?
A. Litre
B. gm
C. kg
D. c.c
Absorption factor, for a fixed degree of absorption from a fixed amount of gas should be_________________?
A. < 1
B. > 1
C. 1
D. ≤ 1
Mechanical Operations Mcqs
The recovery of penicillin from the acidified fermentation broth is done by__________________?
A. Evaporation
B. Distillation
C. Absorption
D. Liquid extraction
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. Percolation
B. Decoction
C. Elutriation or elution
D. None of these
With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux__________________?
A. Remain same
B. Decreases
C. Increases
D. May increase or decrease; depends on system
In McCabe-Thiele method, at infinite reflux ratio________________?
A. The overhead product is minimum
B. Both the operating lines coincide with diagonal
C. Both of the above
D. Neither of the above
(NRe . NSc) is termed in mass transfer operation as the ______________ number?
A. Sherwood
B. Stanton
C. Peclet
D. None of these
The film penetration model of mass transfer was enunciated by______________________?
A. Stefan
B. Toor and Marcello
C. Gilliland
D. Fick
Pick out the system with minimum boiling azeotrope at 1 atm ?
A. Hydrochloric acid-water
B. Ethyl alcohol-water
C. Benzene-toluene
D. All A., B. and C.
Calcium ammonium nitrate (a fertiliser) is dried in a _________________ dryer?
A. Rotary
B. Tunnel
C. Vacuum
D. Tray
Raoult’s law is applicable to the_____________________?
A. Ideal solutions
B. Mixture of water and alcohol
C. Real solutions
D. Non-ideal gases
Flooding in a column results due to___________________?
A. High pressure drop
B. Low velocity of the liquid
C. Low pressure drop
D. High temperature
When the liquid phase and vapour phase of a binary system obeys Raoult’s and Dalton’s law respectively, the relative volatility is the ratio of________________________?
A. Vapour pressure of component A to that of component B
B. Vapour pressure of component A to the partial pressure of A
C. Vapour pressure of component A to the total pressure
D. Partial pressure of component A to the total pressure
Extraction of coffee from its seed is done by___________________?
A. Leaching
B. Liquid-liquid extraction
C. Extractive distillation
D. Steam distillation
Channelling is most severe_____________________?
A. In towers packed with stacked packing
B. In towers packed randomly with crushed solids
C. At very high liquid flow rate
D. In dumped packing of regular units
Which of the following binary systems is an example of a maximum boiling azeotrope ?
A. Water-hydrochloric acid
B. Water-ethyl alcohol
C. Acetone-carbon disulphide
D. n-heptane-n-octane
Which of the following assumes constant molal vaporisation and overflow ?
A. McCabe-Thiele method
B. Plate absorption column
C. Enthalpy concentration method
D. Ponchan-Savarit method
In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of_______________________?
A. Area between operating line and 45° diagonal x-y diagram
B. Tower cross-section
C. Condenser and reboiler surfaces
D. None of these
A liquid mixture contains 30% o-xylene, 60% p-xylene and 10%. m-xylene (all percentages in w/w). Which of the following statements would be true in respect of this mixture ?
A. The mixture exhibits an azeotrope at 101.3 kPa
B. The composition of the mixture in mole percent is: o-xylene 30, p-xylene 60 and m-xyoene 10
C. The composition of the mixture, in percent by volume is: o-xylene 30, p-xylene 60. and mxylene 10
D. The mixture contain optical isomers
For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will_____________________?
A. Increase
B. Remain same
C. Decrease
D. Data insufficient, can’t be predicted
Which of the following is an undesirable characteristic for the solvent used in gas absorption ?
A. Low viscosity
B. Low vapor pressure
C. High gas solubility
D. None of these
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. Same as
B. More than
C. Less than
D. Very much less