SHORT AND MULTIPLE CHOICE QUESTIONS 1. Explain the basic difference between the mass transfer coefficients ky and ky. 2. Obtain the relation between kY and kY. Write down the units of mass transfer coefficients. Discuss when and how the mass transfer coefficients depend upon concentration. 3. Give the physical significances of the dimensionless groups in mass transfer. 4. For mass transfer from a sphere to a stagnant liquid, show that Sh=2. 5. Explain the underlying assumptions of the theories of mass transfer. 6. Derive Eqs. (3.34) and (3.39). 7. The film theory gives a linear concentration profile of the solute within the stagnant film. Is there a point within the film at which the gradient of 'true concentration profile' and that of the 'theoretical concentration' profile in the film are the same? 8. Discuss the importance and applications of mass transfer analogies. 9. A gas A diffuses through a non-diffusing B across a stagnant film of thickness 2mm. Given: mole fractions of A on the two sides of the film are yA1=0.3,yA2=0.05; total pressure =1atm; molar flux, NA=5104kmol/m2s