Mass Transfer – Multiple Choice Questions (MCQs)

1. 37. What is the 'equilibrium curve' in mass transfer operations?

   • A. A plot showing the relationship between concentrations in two phases at equilibrium
   • B. A plot showing reaction kinetics
   • C. A plot showing fluid flow characteristics
   • D. A plot showing temperature profiles

2. 38. What is the 'number of transfer units' (NTU)?

   • A. A measure of the difficulty of a separation
   • B. The number of theoretical stages
   • C. The efficiency of a column
   • D. The height of a column

3. 39. What is the 'height of a transfer unit' (HTU)?

   • A. The height of a column section equivalent to one transfer unit
   • B. The total height of the column
   • C. The diameter of the column
   • D. The packing height

4. 40. For absorption, what is the 'absorption factor' (A)?

   • A. L/(mV)
   • B. V/(mL)
   • C. m/L
   • D. m/V

5. 41. What is the 'stripping factor' (S)?

   • A. L/(mV)
   • B. V/(mL)
   • C. m/L
   • D. m/V

6. 42. What is the 'operating line' in absorption/stripping?

   • A. A line representing the actual operating conditions of the column
   • B. A line representing equilibrium conditions
   • C. A line representing ideal stages
   • D. A line representing minimum flow rates

7. 43. In gas absorption, if the operating line is above the equilibrium curve, what does it indicate?

   • A. The absorption is possible
   • B. The absorption is impossible
   • C. The system is at equilibrium
   • D. The solvent flow rate is too low

8. 44. In gas absorption, if the operating line is below the equilibrium curve, what does it indicate?

   • A. The absorption is possible
   • B. The absorption is impossible
   • C. The system is at equilibrium
   • D. The solvent flow rate is too high

9. 45. What is 'diffusion through a stagnant film' model?

   • A. A model assuming that resistance to mass transfer is concentrated in thin films near the interface
   • B. A model for turbulent diffusion
   • C. A model for diffusion in solids
   • D. A model for molecular diffusion in bulk fluid

10. 46. What is 'equimolar counterdiffusion'?

    • A. Diffusion where the molar fluxes of two components are equal and opposite
    • B. Diffusion where one component is stagnant
    • C. Diffusion with chemical reaction
    • D. Diffusion in a single phase

11. 47. What is 'diffusion through a stagnant film of a non-diffusing component'?

    • A. Diffusion where one component is stagnant
    • B. Diffusion where both components are diffusing
    • C. Diffusion with chemical reaction
    • D. Diffusion in solids

12. 48. What is the 'Schmidt number' (Sc)?

    • A. Ratio of momentum diffusivity to mass diffusivity
    • B. Ratio of thermal diffusivity to momentum diffusivity
    • C. Ratio of mass diffusivity to thermal diffusivity
    • D. Ratio of heat transfer to mass transfer