Mass Transfer Set 6

Mechanical Engineering

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This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 6

Q1 | The minimum liquid rate to be used in an absorber corresponds to an operating line
  • Of slope = 1
  • Of slope = 0.1
  • Tangential to the equilibrium curve
  • None of these
Answer: Tangential to the equilibrium curve
Q2 | Leaching of uranium ore and gold ore is done in
  • Centrifugal extractor
  • Pachuca tanks
  • Bollman extractor
  • None of these
Answer: Pachuca tanks
Q3 | The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is
  • 0
  • ?
  • #NAME?
  • #NAME?
Answer: #NAME?
Q4 | For a ternary mixture, in which equilateral triangular co-ordinate is used in leaching and extraction, a __________ of the equilateral triangular co-ordinates.
  • Binary mixture is represented by the apex
  • Binary mixture is represented by any point inside
  • Ternary mixture is represented by the sides
  • Pure component is represented by the apex
Answer: Pure component is represented by the apex
Q5 | In a gas-liquid absorption column, for obtaining the maximum absorption efficiency
  • Liquid stream should be distributed uniformly
  • Gas stream should be distributed uniformly
  • Both gas as well as liquid streams should be distributed uniformly
  • By passing should be completely avoided
Answer: Both gas as well as liquid streams should be distributed uniformly
Q6 | To get high tray efficiency
  • Interfacial surface between liquid and gas phase should be large
  • Time of contact between the two phases should be less
  • Gas velocity should be very low
  • Liquid entrainment should be severe
Answer: Interfacial surface between liquid and gas phase should be large
Q7 | Lewis number (Le) is
  • Sc × Pr
  • Pr × St
  • Sh × Pr
  • St × Sh
Answer: Sc × Pr
Q8 | Which is not concerned directly with mass transfer?
  • Schmidt number
  • Sherwood number
  • Lewis relationship
  • Froude number
Answer: Froude number
Q9 | Most important factor to be considered in the selection of packings for absorbers is the __________ of packing.
  • Size
  • Durability
  • Porosity
  • Cost
Answer: Porosity
Q10 | For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement.
  • No change in theoretical
  • Marginal decrease in the number of
  • Major decrease in the number of
  • None of these
Answer: Marginal decrease in the number of
Q11 | Experimental determination of __________ is done by wetted wall column method.
  • Diffusion co-efficient
  • Mass transfer co-efficient
  • NTU
  • None of these
Answer: Mass transfer co-efficient
Q12 | Ammonia present in the coke oven gas is removed by washing with
  • Caustic solution
  • Dilute ammoniacal liquor
  • Dilute HCl
  • Ethanolamine
Answer: Dilute ammoniacal liquor
Q13 | Which of the following provides maximum contact surface for a liquid-vapour system?
  • Packed tower
  • Bubble-cap plate column
  • Sieve-plate column
  • Wetted wall column
Answer: Packed tower
Q14 | At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes
  • 1
  • 0
  • ?
  • None of these
Answer: ?
Q15 | Measurement of the interfacial area of mass transfer is achieved easily & accurately in case of a __________ column.
  • Spray
  • Packed
  • Bubble cap plate
  • Wetted wall
Answer: Wetted wall
Q16 | Which of the following is directly concerned with Psychrometry?
  • Lewis relationship
  • Galileo number
  • Weber number
  • Dean number
Answer: Lewis relationship
Q17 | 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
  • At ground level
  • 2 metres above the ground
  • 5 metres above ground
  • 10 metres above ground
Answer: At ground level
Q18 | Which of the following is an undesirable property in a tower packing?
  • Large surface per unit volume
  • Large free cross-section
  • Low weight per unit volume
  • Large weight of liquid retained
Answer: Large weight of liquid retained
Q19 | High pressure at the bottom of a distillation tower handling heat sensitive materials results in
  • Thermal decomposition of bottoms
  • Increased relative volatility
  • Erosion of the tower
  • Very efficient operation
Answer: Thermal decomposition of bottoms
Q20 | Steady state equimolal counter diffusion is encountered in
  • Separation of a binary mixture by distillation
  • Absorption of NH3 from air by water
  • All liquid-liquid diffusion systems
  • All liquid-solid diffusion systems
Answer: Separation of a binary mixture by distillation
Q21 | Minimum reflux ratio in a distillation column results in
  • Optimum number of trays
  • Minimum reboiler size
  • Maximum condenser size
  • Minimum number of trays
Answer: Maximum condenser size
Q22 | In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of
  • 1.5
  • -0.6
  • -1.5
  • 0.6
Answer: -1.5
Q23 | The individual mass transfer co-efficients (moles/m2 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?
  • Liquid side
  • Gas side
  • Interfacial
  • Both liquid and gas side
Answer: Gas side
Q24 | Steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapour-gas mixture is called the __________ temperature.
  • Dry-bulb
  • Wet-bulb
  • Dew point
  • Adiabatic saturation
Answer: Wet-bulb
Q25 | In case of unsaturated air
  • Dew point < wet bulb temperature
  • Wet bulb temperature < dry bulb temperature
  • Both (A) and (B)
  • Neither (A) not (B)
Answer: Both (A) and (B)
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