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This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 10

Q1 | Free flowing granular materials can be best dried in a __________ drier.
  • Rotary
  • Cylinder
  • Drum
  • Freeze
Q2 | In a packed bed absorption column, the channelling will be noted by the
  • Increase in flow rate
  • Sharp drop in pressure drop
  • Sharp rise in pressure drop
  • None of these
Q3 | The ratio of Murphree plate efficiency to point efficiency is always > 1 in a __________ flow model.
  • Plug
  • Perfectly mixed
  • Both (A) & (B)
  • Neither (A) nor (B)
Q4 | Fractional solvent extraction
  • Employs only one solvent
  • Employs two solvents
  • Results in low interfacial tension
  • None of these
Q5 | At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid__________ that in dry packed tower.
  • Is greater than
  • Is lower than
  • Is same as
  • Cannot be predicted as data are insufficient
Q6 | During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the __________ remains constant.
  • Wet bulb temperature
  • Partial pressure of water vapor
  • Relative humidity
  • None of these
Q7 | Wet bulb and dry bulb temperatures becomes identical at __________ percent saturationcurve.
  • 100
  • 50
  • 78
  • None of these
Q8 | __________ is the separation technique used for desalination of sea water.
  • Thermal diffusion
  • Reverse osmosis
  • Adsorption
  • Absorption
Q9 | The partial pressure distribution of an ideal gas diffusing through another stagnant idealgas at steady state follows a/an __________ law.
  • Exponential
  • Parabolic
  • Linear
  • Cubic
Q10 | Out of two equilibrium curves, first one lies above the diagonal and the second lies below the diagonal in the x-y plot. It means that separation by distillation is
  • Not possible in the second case unless vacuum is applied
  • Not possible in the second case unless high pressure is applied
  • More readily done in the second case compared to first one
  • None of these
Q11 | According to Chilton-Colburn analogy for mass transfer, NSt.NSc 2/3 is equal to
  • f
  • f/2
  • 2f
  • 1/f
Q12 | Very tall packed towers are divided into series of beds to
  • Reduce the overall pressure drop
  • Avoid channelling
  • Reduce liquid hold-up
  • Avoid flooding
Q13 | If „f’ is defined as above, then which of the following applies to a feed at dew point?
  • f = 1
  • f < 1
  • f > 1
  • 0 < f < 1
Q14 | Separation of the isotopes of helium for scientific investigations is done by
  • Reverse osmosis
  • Thermal diffusion
  • Leaching
  • Solvent extraction
Q15 | Flash distillation is suitable for the separation of components
  • Having very close boiling points
  • Which form maximum boiling azeotrope
  • Having very wide boiling points
  • Which form minimum boiling azeotrope
Q16 | The McCabe ?L law states that the
  • Molar heats of vaporisation of components are nearly equal
  • Linear crystal growth rate depends on the degree of super-saturation
  • Linear crystal growth rate does not depend on the crystal size
  • Linear crystal growth rate depends on the crystal size
Q17 | When both the fluids flow concurrently in an absorber, the slope of the operating line is
  • #NAME?
  • #NAME?
  • 1
  • -1
Q18 | Steam distillation is used for separation of high boiling
  • Substances from non-volatile impurities
  • Volatile impurity from still higher boiling substances
  • Both (A) and (B)
  • Neither (A) nor (B)
Q19 | The relative saturation of a partially saturated mixture of vapour and gas can be increasedby __________ of the mixture.
  • Reducing the total pressure
  • Increasing the total pressure
  • Reducing the temperature
  • Both (B) and (C)
Q20 | Pick out the correct statement.
  • Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation
  • A sharp decrease in pressure drop is an indication of flooding in a distillation coloumn
  • Solvent used in extractive distillation should be of high volatility
  • Flash distillation is suitable for separating components which have very close boiling temperature
Q21 | Pick out the wrong statement.
  • Constant pressure distillation cannot separate an Azeotropic mixture
  • Relative volatility of a binary mixture changes appreciably with the minor change in temperature
  • The relative volatility of a binary mixture at Azeotropic composition is unity
  • Flash distillation is practised on wide spread scale in petroleum refinery
Q22 | For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottom product streams
  • Increases
  • Decreases
  • Remain unaffected
  • Passes through a maximum
Q23 | __________ diffusion is used for separating the isotopes of methane.
  • Thermal
  • Pressure
  • Concentration
  • Force
Q24 | Pick out the wrong statement.
  • The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one
  • Sherwood number for flow in pipes can be expressed as the ratio of the concentration gradient at wall to the overall concentration difference
  • According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2
  • The z-component of the total mass flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz
Q25 | For a distillation column operating at minimum reflux, the
  • Concentration of liquid and vapour leaving a plate will be same
  • Reflux ratio will be maximum
  • Number of plates required will be maximum
  • None of these