Mass Transfer – Multiple Choice Questions (MCQs)

1. 61. What is 'weeping' in a plate column?

   • A. Liquid falling through the perforations of the tray due to insufficient vapor flow
   • B. Excessive vapor flow
   • C. Liquid overflowing the downcomer
   • D. Liquid getting entrained with vapor

2. 62. What is 'entrainment' in a plate column?

   • A. Liquid droplets being carried upward by the vapor stream to the tray above
   • B. Liquid falling through the tray
   • C. Vapor bypassing the tray
   • D. Foaming on the tray

3. 63. What is the 'Murphree tray efficiency'?

   • A. A measure of the actual separation achieved on a tray compared to an ideal tray
   • B. The overall column efficiency
   • C. The efficiency of the reboiler
   • D. The efficiency of the condenser

4. 64. What is the driving force for mass transfer in liquid-liquid extraction?

   • A. Concentration difference in the two liquid phases
   • B. Temperature difference
   • C. Pressure difference
   • D. Density difference

5. 65. What is a 'ternary phase diagram' used for in liquid-liquid extraction?

   • A. To represent the equilibrium compositions of three components
   • B. To represent temperature profiles
   • C. To represent pressure profiles
   • D. To represent reaction kinetics

6. 66. What is a 'tie line' on a ternary phase diagram?

   • A. A line connecting the compositions of two immiscible phases in equilibrium
   • B. A line representing a single phase
   • C. A line representing a boiling point
   • D. A line representing a critical point

7. 67. What is 'solvent' in extraction?

   • A. The liquid that selectively dissolves the solute
   • B. The liquid that is being extracted
   • C. The solid component
   • D. The gaseous component

8. 68. What is 'raffinate' in extraction?

   • A. The phase that contains the unextracted components and solvent
   • B. The phase that contains the extracted solute and solvent
   • C. The feed solution
   • D. The extracting solvent

9. 69. What is 'extract' in extraction?

   • A. The phase that contains the unextracted components and solvent
   • B. The phase that contains the extracted solute and solvent
   • C. The feed solution
   • D. The extracting solvent

10. 70. What is the 'distribution coefficient' (K_D) in extraction?

    • A. The ratio of the concentration of a solute in the extract phase to its concentration in the raffinate phase at equilibrium
    • B. The ratio of viscosities
    • C. The ratio of densities
    • D. The ratio of boiling points

11. 71. What is 'washing' in extraction?

    • A. A step to remove residual solvent from the raffinate or extract phase
    • B. A step to increase the solute concentration
    • C. A step to introduce new solvent
    • D. A step to heat the solution

12. 72. What is the driving force for mass transfer in drying?

    • A. Partial pressure difference of water vapor
    • B. Temperature difference
    • C. Absolute humidity difference
    • D. Total pressure difference