Question Bank - Mass Transfer MCQ Test - Set 29 - ObjectiveBooks

# Practice Test: Question Set - 29

1. __________ columns are used for liquid dispersion in a continuous gas phase.
(A) Packed
(B) Pulse
(C) Bubble cap
(D) Sieve plate

2. Pick out the wrong statement.
(A) When the concentration difference for the mass transfer becomes zero at the bottom of the gas absorption tower, then the upper end of the operating line touches the equilibrium curve
(B) The average distance between the operating line and equilibrium line is large, when the liquid-gas ratio is also large in case of a counter current gas absorption tower
(C) The operating line lies above the equilibrium curve in case of a gas desorber
(D) With decrease in the liquid flow rate for a fixed gas flow rate, the slope of the operating line decreases, in case of gas absorption process

3. An alkaline solution is used to reduce the concentration of carbon dioxide in a stream from 10% to 0.1% by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is:
(A) 9.21
(B) 4.605
(C) 100
(D) 0.001

4. The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by
(A) Increasing the gas film co-efficient
(B) Increasing the liquid film co-efficient
(C) Increasing the total pressure
(D) Decreasing the total pressure

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
(A) Higher dew point
(B) Higher absolute (specific) humidity
(C) Higher relative humidity
(D) Higher wet bulb temperature

6. When the psychometric ratio is __________ then the adiabatic saturation temperature and wet bulb temperature becomes equal.
(A) 1
(B) < 1
(C) > 1
(D)

7. With increase in the concentration of the adsorbate, the integral heat of adsorption
(A) Increases
(B) Decreases
(C) Remains unchanged
(D) May increase or decrease; depends on the type of adsorbate

8. Use of raschig rings in place of crushed stones as packing in packed beds (other things being same)
(A) Increases pressure drop, increases surface area
(B) Increases pressure drop, decreases surface area
(C) Decreases pressure drop, increases surface area
(D) Decreases pressure drop, decreases surface area

9. A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process?
(A) Flow rate of inlet air
(B) Relative humidity of outlet air
(C) Humidity of inlet air
(D) Temperature of the solid

10. Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the
(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) Multi-component distillation is involved

11. When the __________ the relative humidity of air decreases, despite an increase in the absolute humidity.
(A) Temperature rises
(B) Pressure rises
(C) Temperature falls
(D) Pressure falls

12. Pick out the wrong statement.
(A) Critical moisture content is not a property of the material itself
(B) A sharp increase in pressure drop gives an indication of the flooding in a distillation column
(C) Separation of components is not possible in liquid extraction, if selectivity is unity
(D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum

13. Detergent solution is dried to a powder in a
(A) Spray dryer
(B) Spouted bed dryer
(C) Tunnel dryer
(D) Pan open to atmosphere

14. Stefan's law describes the mass transfer by
(A) Diffusion
(B) Bulk flow
(C) Both 'a' & 'b'
(D) Neither 'a' nor 'b'

15. Which of the following equipments is not used in liquid-liquid extraction?
(A) Pachuka tank
(B) Agitated vessels
(C) Centrifugal extractors
(D) Packed towers

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