Mass Transfer Set 21

Mechanical Engineering

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This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 21

Q1 | __________ developed the film theory.
  • Higbie
  • Fick
  • Ergun
  • Levenspiel
Answer: Higbie
Q2 | Hydrogenation of oil is carried out in a/an __________ in Vanaspati manufacturing plant.
  • Agitated vessel
  • Sieve tray column
  • Bubble cap column
  • Packed tower
Answer: Agitated vessel
Q3 | Schmidt number is given by
  • µ/?DAB
  • Re × Pe
  • Sh × Pe
  • Re/Pe
Answer: µ/?DAB
Q4 | Pick out the correct statement.
  • Diffusivity decreases with increase in temperature
  • Diffusivity increases with increase in molecular weight
  • Diffusivity increases with the size of the individual molecule
  • None of these
Answer: None of these
Q5 | Fenske equation determines the
  • Maximum number of ideal plates
  • Height of the distillation column
  • Minimum number of theoretical plates
  • Optimum reflux ratio
Answer: Minimum number of theoretical plates
Q6 | If xD = overhead product molal composition and RD = reflux ratio, then slope and intercept of the operating line for rectifying section are respectively
  • [xD/(RD + 1)], [RD/(RD + 1)]
  • [RD/(RD + 1)], [xD/(xD + 1)]
  • [xD/(RD + 1)], [(RD + 1)/RD]
  • None of these
Answer: [RD/(RD + 1)], [xD/(xD + 1)]
Q7 | Which of the following equipments is not used for gas dispersion?
  • Agitated vessels
  • Bubble cap tray towers
  • Perforated sieve tray towers
  • Spray towers
Answer: Spray towers
Q8 | __________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids.
  • Wetted wall
  • Packed
  • Plate
  • Spray
Answer: Plate
Q9 | When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption.
  • Always lower than
  • Always higher than
  • Same as
  • Dependent on the system; can be either lower or higher than
Answer: Always lower than
Q10 | On addition of solute in the solvent, the __________ of the solution decreases.
  • Boiling point
  • Freezing point
  • Vapour pressure
  • Both (B) and (C)
Answer: Both (B) and (C)
Q11 | Extraction of penicillin employs a __________ extraction column.
  • Centrifugal
  • Packed
  • Plate
  • None of these
Answer: Centrifugal
Q12 | Which of these columns incurs the lowest pressure drop?
  • Packed column (with stacked packing)
  • Packed column (with dumped packing)
  • Bubble plate column
  • Pulse column
Answer: Packed column (with stacked packing)
Q13 | 'Absorption with chemical reaction' is involved in the removal of
  • Carbon dioxide from gaseous stream using alkaline solution
  • Benzol from coke oven gas using solar oil/wash oil
  • Ammonia from coke oven gas using refrigerated water
  • Tar from coke oven gas in primary gas coolers using chilled water
Answer: Carbon dioxide from gaseous stream using alkaline solution
Q14 | Which of the following mixtures does not form an azeotrope at atmospheric pressure?
  • Water-alcohol
  • Methyl alcohol-acetone
  • Butyl acetate-water
  • None of these
Answer: None of these
Q15 | In batch distillation with constant reflux, overhead product composition __________ with time.
  • Increases
  • Decreases
  • Does not vary
  • May increase on decrease, depends on the system
Answer: Decreases
Q16 | McCabe-Thiele method of binary distillation does not assume that the
  • Sensible heat changes are negligible compared with latent heat changes
  • Molar latent heats of all components are equal
  • Heat of mixing is negligible
  • None of these
Answer: None of these
Q17 | Which of the following same diameter columns gives lowest pressure drop per unit height?
  • Bubble-cap column
  • Sieve-plate column
  • Packed column (stacked)
  • Randomly packed column
Answer: Packed column (stacked)
Q18 | Absorption factor method is used to calculate the number of ideal stages, when
  • Operating line lies above the equilibrium line
  • Operating line lies below the equilibrium line
  • Both operating and equilibrium lines are parallel
  • Pressure drop in the column is very high
Answer: Both operating and equilibrium lines are parallel
Q19 | Entrainer used in Azeotropic distillation should
  • Form a low boiling azeotrope with one of the constituents of the mixture
  • Form a new azeotrope of low relative volatility with one of the constituents of the mixture
  • Have high latent heat of vaporisation
  • Have high viscosity to provide high tray efficiency
Answer: Form a low boiling azeotrope with one of the constituents of the mixture
Q20 | A plait point is the point on the solubility curve, where the tie line reduces to a point. What is the number of plait point for a ternary system containing two pairs of partially miscible liquids?
  • Zero
  • 1
  • 2
  • 3
Answer: Zero
Q21 | For the same process conditions, the reflux ratio of an unlagged distillation column
  • Decreases in winter
  • Increases in winter
  • Increases in summer
  • None of these
Answer: Increases in winter
Q22 | Minimum possible diameter of a packed column is decided mainly by the
  • Flooding
  • Gas viscosity
  • Liquid density
  • Liquid hold up
Answer: Flooding
Q23 | Ponchon-Savarit method analyses the fractional equipment based on
  • Enthalpy balance only
  • Material balance only
  • Both enthalpy and material balances
  • The assumption of constant molal-overflow
Answer: Both enthalpy and material balances
Q24 | Dryer widely used in a textile industry is __________ dryer.
  • Festoon
  • Cylinder
  • Conveyor
  • Tunnel
Answer: Conveyor
Q25 | Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty?
  • Sieve plate column
  • Bubble cap column
  • Randomly packed column
  • Wetted wall column
Answer: Wetted wall column
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