Mass Transfer – Multiple Choice Questions (MCQs)

1. 73. What is the 'constant rate period' in drying?

   • A. The period where the rate of drying is constant and independent of moisture content
   • B. The period where the rate of drying decreases
   • C. The period where the material is completely dry
   • D. The period where the temperature of the material increases rapidly

2. 74. What is the 'falling rate period' in drying?

   • A. The period where the rate of drying is constant
   • B. The period where the rate of drying decreases as moisture content decreases
   • C. The period where the material is completely dry
   • D. The period where the temperature of the material decreases rapidly

3. 75. What is 'bound moisture' in drying?

   • A. Moisture held within the solid pores and bound by capillary and surface forces
   • B. Moisture that is easily removed by evaporation
   • C. Moisture on the surface of the solid
   • D. Moisture that cannot be removed by drying

4. 76. What is 'unbound moisture' in drying?

   • A. Moisture in excess of the equilibrium moisture content
   • B. Moisture that is strongly bound to the solid
   • C. Moisture that cannot be removed
   • D. Moisture in the air

5. 77. What is 'equilibrium moisture content'?

   • A. The moisture content of a solid in equilibrium with the surrounding air at a given temperature and humidity
   • B. The moisture content at the start of drying
   • C. The moisture content after complete drying
   • D. The moisture content of the air

6. 78. What is 'critical moisture content' in drying?

   • A. The moisture content at which the constant rate drying period ends and the falling rate period begins
   • B. The moisture content at which drying starts
   • C. The moisture content when the material is completely dry
   • D. The maximum moisture content of a material

7. 79. What is 'humid volume'?

   • A. Volume of moist air per unit mass of dry air
   • B. Volume of dry air per unit mass of moist air
   • C. Volume of water vapor
   • D. Volume of liquid water

8. 80. What is 'humid heat'?

   • A. Heat capacity of moist air per unit mass of dry air
   • B. Heat capacity of water vapor
   • C. Heat capacity of dry air
   • D. Heat transferred during humidification

9. 81. Which of the following is a key parameter for crystallizer design?

   • A. Supersaturation
   • B. Relative volatility
   • C. Viscosity
   • D. Density

10. 82. What is 'supersaturation' in crystallization?

    • A. A condition where the solute concentration in a solution is higher than its equilibrium solubility at that temperature
    • B. A condition where the solution is unsaturated
    • C. A condition where the solution is dilute
    • D. A condition where the solution is boiling

11. 83. What is the 'driving force' for crystallization?

    • A. Supersaturation
    • B. Temperature difference
    • C. Pressure difference
    • D. Density difference

12. 84. What is the role of 'nucleation' in crystallization?

    • A. The initial formation of tiny crystal particles
    • B. The growth of existing crystals
    • C. The separation of crystals from solution
    • D. The dissolution of crystals