Mass Transfer problems
- 1. Which of the following remains constant during sensible cooling process?
Options- A. Specific humidity
- B. Partial pressure of vapour
- C. Both (a) and (b)
- D. Neither (a) nor (b) Discuss
Correct Answer: Both (a) and (b)
- 2. 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
Correct Answer: higher relative humidity
- 3. 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
Correct Answer: decreases with decrease in pressure.
- 4. 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
Correct Answer: increase 'S' and decrease 'G'.
- 5. 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
Correct Answer: hot water entering the tower and the cooled water leaving the tower.
- 6. 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
Correct Answer: allowable gas and liquid velocities.
- 7. 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 Discuss
Correct Answer: 1
- 8. 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
Correct Answer: +ve
- 9. 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
Correct Answer: S1/S2
- 10. 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
Correct Answer: relative volatility is reasonably constant.
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