Mass Transfer Operations - I Mid - I, September - 2014

1.Mass transfer is a result
  • concentration difference
  • diffusion
  • both a and b
  • none of the these
Answer: C
2.Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as
  • K  D
  • K √D
  • K D1.5
  • K D2
Answer: A
3.Corresponding to Prandtl number in heat transfer the dimensionless group in mass transfer is
  • Schmidt number
  • Sherwood number
  • peclet number
  • none of these
Answer: D
4.The unit of diffusion coefficient
  • m2/s
  • m/s
  • mole/ m.s
  • none of these
Answer: A
5.Prandtl number of gases is nearly
  • 2
  • 3
  • 4
  • 1
Answer: C
6.The binary diffusivity in gases varies
  • Directly as the pressure
  • inversely as the pressure
  • Inversely as the square root of pressure
  • Directly as the square root of pressure
Answer: B
7.Prandtl number is the ratio of
  • Momentum and mass diffusivity
  • Momentum & thermal diffusivity
  • Mass and Momentum diffusivity
  • Thermal and mass diffusivity
Answer: B
8.The analogous number in Mass transfer corresponding to Nusselt number is
  • Re
  • Pe
  • Pr
  • Sh
Answer: D
9.The eddy diffusion occurs when
  • one of the fluid is in turbulent motion
  • both fluids are in laminar motion
  • both a and b
  • none of these
Answer: A
10.Mass transfer rate between two fluid phases does not necessarily depend on the __________ of the two phases.
  • Chemical properties
  • physical properties
  • degree of turbulence
  • interfacial area
Answer: A
11.The value of NA /(NA + NB) for the case of steady state equimolar counter diffusion of A & B is ______________________________
Answer: Intermediate
12.The vapor phase produced directly from the solid phase is called ________________
Answer: Sublimation
13.If there is a difference in absolute pressure across a porous solid ______________ flow will occur
Answer: Hydrodynamic
14.peclet number is the product of Re and ______________________
Answer: pranditl number
15.The flux of A is given by NA in terms of Ky and yAG and yA is ______________
Answer: Ky (yAG - y *)
16.Surface renewal theory was developed by ______________________.
Answer: DANCKWERTS
17.Film theory was developed by ___________________.
Answer: Higbie
18.Steady state equimolar counter diffusion equation is ____________________.
Answer: NA = DAB * Pt / RTZ * (y1 – y2)
19.Mass transfer coefficient is also called as __________________.
Answer: Film Co-efficient
20.The diffusivity DAB for A diffusing B is same as the diffusivity DBA for B diffusing in A for binary mixture of ___________________ only
Answer: deal gasses only