Convective Mass Transfer MCQ

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• What will be the flux through the convective mass transfer when the mass transfer coefficient is 2 × 10-8 m/s and the change in the concentration is 25000 kg-mole/m3 and the eddy diffusion is 3 × 10-6 m2/s?
  ক

  0.0005 kg-moles/m2.s

  খ

  0.0020 kg-moles/m2.s

  গ

  0.0015 kg-moles/m2.s

  ঘ

  0.0025 kg-moles/m2.s
• What is convective mass transfer?
  ক

  Combination of molecular diffusion and eddy diffusion

  খ

  Molecular diffusion

  গ

  Eddy diffusion

  ঘ

  Fluid flow
• If the flow of liquid is turbulent, the transfer of solutes will take place due to molecular diffusion.
  ক

  True

  খ

  False
• Which parameter allows the transfer of solute when the liquid flows through a solid surface?
  ক

  Convective mass transfer

  খ

  Heat transfer

  গ

  Fluid flow

  ঘ

  Molecular diffusion
• What is the example of transport of a solute in a liquid flowing through another immiscible liquid?
  ক

  Reverse osmosis

  খ

  Haemodialysis

  গ

  Liquid-liquid extraction

  ঘ

  Diffusion
• What is the example of transport of solute in a liquid flowing through a solid surface?
  ক

  Reverse osmosis

  খ

  Haemodialysis

  গ

  Liquid-liquid extraction

  ঘ

  Diffusion
• The connective mass transfer can be observed in ___________
  ক

  Flowing fluids

  খ

  Stagnant fluid

  গ

  Fluid in bulk

  ঘ

  Solids
• Heat transfer takes place as per ______________
  ক

  Zeroth law of thermodynamics

  খ

  First law of thermodynamics

  গ

  Second law of thermodynamics

  ঘ

  Kirchoff’s law
• Which is the fastest mode of transfer of heat?
  ক

  Conduction

  খ

  Convection

  গ

  Scattering

  ঘ

  Radiation
• Convection is faster than conduction?
  ক

  True

  খ

  False
• Heat transfer by molecular collision in ____________________
  ক

  Conduction

  খ

  Convection

  গ

  Scattering

  ঘ

  Radiation
• Which type of columns are used for liquid dispersion in a continuous gas phase?
  ক

  Packed

  খ

  Bubble cap

  গ

  Sieve – plate

  ঘ

  Fluidized bed
• Psychrometry deals with between which type of phases?
  ক

  Gas-liquid

  খ

  Gas-solid

  গ

  Gas-Vapour

  ঘ

  Vapour-Solid
• Refer to Q8 and, calculate the rate of loss of naphthalene from the surface per unit width.
  ক

  0.100 gmol/m.hr

  খ

  0.102 gmol/m.hr

  গ

  0.101 gmol/m.hr

  ঘ

  0.103 gmol/m.hr
• A stream of air at 100 kPa pressure and 300 K is flowing on the top surface of a thin flat sheet of solid naphthalene of length 0.2 m with a velocity of 20 m/sec. The other data are: Mass diffusivity of naphthalene vapor in air = 6 * 10 –6 m2/sec Kinematic viscosity of air = 1.5 * 10 –5 m2.sc Concentration of naphthalene at the air-solid naphthalene interface = 1 * 10 – 5 kmol/m3 Calculate the overage mass transfer coefficient over the flat plate. Note: For heat transfer over a flat plate, convective heat transfer coefficient for laminar flow can be calculated by the equation. Nu = 0.664 ReL1/2 Pr1/3 you may use analogy between mass and heat transfer.
  ক

  0.014 m/sec

  খ

  0.015 m/sec

  গ

  0.016 m/sec

  ঘ

  0.013 m/sec
• What do you mean by Sherwood number?
  ক

  Dimension mass transfer number

  খ

  Dimensionless mass transfer number

  গ

  Dimension momentum transfer number

  ঘ

  Dimensionless momentum transfer number
• In a wetted-wall tower, an air-H2S mixture is flowing by a film of water which is flowing as a thin film down a vertical plate. The H2S is being absorbed from the air to the water at a total pressure of 1.50 atm abs and 30oC. The value of kc of 9.567×10-4 m/s has been predicted for the gas-phase mass-transfer coefficient. At a given point the mole fraction of H2S in the liquid at the liquid-gas interface is 2.0×10-5 and pA of H2S in the gas is 0.05 atm. The Henry’s law equilibrium relation is pA(atm) = 609xA (mole fraction in liquid). Calculate the rate of absorption of H2S.
  ক

  1.480×10-3 kmol/m2.s

  খ

  1.486×10-3 kmol/m2.s
• The distribution coefficient is accurate only if?
  ক

  Solvents are miscible

  খ

  Solutes are miscible

  গ

  Solvents are immiscible

  ঘ

  Occurrence of chemical reaction
• In the two-phase aqueous systems, in ordinary situations the bulk phases are not in equilibrium?
  ক

  True

  খ

  False
• Rate of mass transfer is inversely proportional to the rate of reaction at solid surface?
  ক

  True

  খ

  False
• The unit of mass transfer coefficient is ______________
  ক

  m-1s

  খ

  ms-1

  গ

  m-1s2

  ঘ

  m2s-1
• Convection does not occur in _______________
  ক

  Solid

  খ

  Liquid

  গ

  Gas

  ঘ

  Molten Solid
• Which number forms the connecting link between the temperature and concentration profiles?
  ক

  Prandtl number

  খ

  Schmidt number

  গ

  Fourier number

  ঘ

  Lewis number
• Which number forms the connecting link between the velocity and concentration profiles?
  ক

  Schmidt number

  খ

  Reynolds number

  গ

  Stanton number

  ঘ

  Fourier number
• Which number forms the connecting link between the velocity and temperature profiles?
  ক

  Fourier number

  খ

  Prandtl number

  গ

  Stanton number

  ঘ

  Biot number
• Convective mass transfer involves the transportation of material between a boundary surface and a moving fluid or between two immiscible fluids. It is prescribed by the relation
  ক

  2 h m (d C B)

  খ

  ½ h m (d C B)

  গ

  h m (d C B)

  ঘ

  3/2 h m (d C B)
• The solution for velocity, concentration and temperature boundary layers will be same if
  ক

  Prandtl number = Schmidt number= Lewis number

  খ

  Prandtl number = 2 Schmidt number= Lewis number

  গ

  Prandtl number = Schmidt number= 2 Lewis number

  ঘ

  2 Prandtl number = Schmidt number= Lewis number
• Sherwood number is given by
  ক

  3/2 h m L/D

  খ

  ½ h m L/D

  গ

  3 h m L/D

  ঘ

  h m L/D
• Schmidt number is given by
  ক

  2 V/D

  খ

  D/V

  গ

  V/D

  ঘ

  2 D/V
• Prandtl number is given by
  ক

  V/α

  খ

  2 V/α

  গ

  3 V/α

  ঘ

  4 V/α