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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