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This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 11

Q1 | 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
  • 25%
  • 50%
  • 70%
  • 90%
Q2 | Mass transfer co-efficient is directly proportional to DAB 0.5, according to __________ theory.
  • Penetration
  • Surface renewal
  • Film
  • None of these
Q3 | Which of the following gas-liquid contacting devices incurs the least pressure drop for aparticular duty?
  • Grid tray tower
  • Perforated tray tower
  • Wetted wall tower
  • Bubble cap tower
Q4 | For experimental determination of mass transfer co-efficient by wetted wall tower, themass transfer area is
  • Calculated
  • Unknown
  • Known
  • Not required
Q5 | With decrease in the throughput (compared with the design capacity) for a bubble capdistillation column, its efficiency
  • Increases
  • Decreases
  • Remain same
  • May increase or decrease; depends on individual design
Q6 | Diameter to height ratio for a raschig ring is
  • 1
  • 0.5
  • 2
  • 8
Q7 | Which of the following operations does not involve leaching?
  • Dissolving gold from ores
  • Dissolving pharmaceutical products from bark or roots
  • Dissolving sugar from the cells of the beet
  • Removing nicotine from its water solution by kerosene
Q8 | Flooding in a distillation column is detected by a sharp
  • Increase in Murphree plate efficiency
  • Decrease in pressure drop
  • Decrease in liquid hold up in the column
  • Increase in pressure drop
Q9 | In case of an ideal solution, the total vapor pressure varies __________ with the composition expressed as mole fraction,
  • Inversely
  • Linearly
  • Exponentially
  • None of these
Q10 | With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system).
  • Increases
  • Decreases
  • Remain unaffected
  • Increases Linearly
Q11 | 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
Q12 | Absorption accompanied by heat evolution results in
  • Increased capacity of the absorber
  • Increase in equilibrium solubility
  • Decrease in equilibrium solubility
  • None of these
Q13 | The solvent used in liquid extraction should not have high latent heat of vaporisation, because
  • The pressure drop and hence the pumping cost will be very high
  • It cannot be recovered by distillation
  • Its recovery cost by distillation may be prohibitively high
  • It will decompose while recovering by distillation
Q14 | Mass transfer co-efficient varies as DAB0.5, according to the __________ theory.
  • Film
  • Surface renewal
  • Penetration
  • None of these
Q15 | The suitable evaporator for concentration of foaming liquids is a __________ evaporator.
  • Long tube
  • Short tube
  • Vacuum
  • Falling film
Q16 | In stripping section of continuous distillation column, the
  • Liquid is stripped of high boiler
  • Liquid is enriched with high boiler
  • Vapour is stripped of low boiler
  • None of these
Q17 | 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)
  • 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
Q18 | The Schmidt number which is defined as, ?/? D, is the ratio of the
  • Momentum diffusivity to the mass diffusivity
  • Thermal diffusivity to the mass diffusivity
  • Momentum diffusivity to the thermal diffusivity
  • None of these
Q19 | NSc/NPr is called the
  • Psychrometric ratio
  • Lewis number
  • Sherwood number
  • Stanton number
Q20 | At constant pressure, with increase of temperature, the dew point will
  • Increase
  • Decrease
  • Remain unchanged
  • Increase/decrease; depends on the temperature
Q21 | Pick out the correct statement.
  • Dialysis process is used for the production of fresh water from brine
  • Electrodialysis is used in the manufacture of NaOH
  • Electrodialysis is used for the refining/purification of petrol
  • Both (B) and (C)
Q22 | The percentage humidity is less than the relative humidity only at __________ percent humidity.
  • Zero
  • Hundred
  • Both zero and hundred
  • None of these
Q23 | 'ADDUCTS' and 'CLATHRATES' are used in case of
  • Extractive distillation
  • Crystallisation
  • Absorption
  • None of these
Q24 | __________ is concerned with the adsorption equilibria.
  • Fick's law
  • Gibb's equation
  • Freundlich equation
  • None of these
Q25 | In most of the vacuum crystalliser, vacuum is generally produced by means of a
  • Suction pump
  • Compressed air jet
  • Steam jet ejector with a barometric condenser
  • None of these