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Home Chemical Engineering Mass Transfer Comments

  • Question
  • The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________


  • Options
  • A. 1
  • B. 0.5
  • C. 10
  • D. 0

  • Correct Answer



  • Mass Transfer problems


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    • 1. In distillation columns, the number of bubble caps per tray primarily depends upon the

    • Options
    • A. allowable liquid velocity.
    • B. allowable gas velocity.
    • C. allowable gas and liquid velocities.
    • D. feed composition.
    • Discuss
    • 2. The term "cooling range" in a cooling tower refers to the difference in the temperature of

    • Options
    • A. cold water leaving the tower and the wet bulb temperature of the surrounding air.
    • B. hot water entering the tower and the wet bulb temperature of the surrounding air.
    • C. hot water entering the tower and the cooled water leaving the tower.
    • D. none of these
    • Discuss
    • 3. To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate)

    • Options
    • A. increase both 'G' and 'S'.
    • B. decrease both 'G' and 'S'.
    • C. increase 'S' and decrease 'G'.
    • D. increase 'G' and decrease 'S'
    • Discuss
    • 4. Dew point of a gas-vapour mixture

    • Options
    • A. increases with temperature rise.
    • B. decreases with temperature rise.
    • C. decreases with decrease in pressure.
    • D. increases with increase in pressure.
    • Discuss
    • 5. Air initially at 101. 3 kPa and 40°C and with a relative humidity of 50%, is cooled at constant pressure to 30°C. The cooled air has a

    • Options
    • A. higher dew point.
    • B. higher absolute (specific) humidity.
    • C. higher relative humidity
    • D. higher wet bulb temperature.
    • Discuss
    • 6. The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is

    • Options
    • A. +ve
    • B. -ve
    • C. zero
    • D. none of these
    • Discuss
    • 7. Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve)

    • Options
    • A. S2/S1
    • B. S1/S2
    • C. S1 - S2
    • D. S1 x S2
    • Discuss
    • 8. Fenske's equation for determining the minimum number of theoretical stages in distillation column holds good, when the

    • Options
    • A. relative volatility is reasonably constant.
    • B. mixture (to be separated) shows negative deviation from ideality.
    • C. mixture (to be separated) shows positive deviation from ideality.
    • D. multicomponent distillation is involved.
    • Discuss
    • 9. Which of the following is the most suitable for extraction in a system having very low density difference?

    • Options
    • A. Mixer-settler extractor
    • B. Centrifugal extractor
    • C. Pulsed extractor
    • D. Packed extraction tower
    • Discuss
    • 10. Low viscosity absorbent is preferred for reasons of

    • Options
    • A. rapid absorption rates and good heat transfer characteristics.
    • B. improved flooding characteristics.
    • C. low pressure drop on pumping.
    • D. all (a), (b) and (c).
    • Discuss


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