Chemical Mass Transfer MCQ Test - Set 01

Practice Test: Question Set - 01


1. Which of the following psychrometric processes is followed by water vapour laden unsaturated air, when it is passed through solid or liquid adsorbent?
    (A) Cooling and dehumidification
    (B) Heating and dehumidification at almost constant wet bulb temperature
    (C) Dehumidification with dry bulb temperature remaining constant
    (D) None of these

2. Heat sensitive materials like certain pharmaceuticals and food stuffs can be dried in a/an __________ dryer.
    (A) Indirect tray
    (B) Spray
    (C) Freeze
    (D) None of these

3. According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the column.
    (A) 5
    (B) 9
    (C) 12
    (D) 28

4. With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible.
    (A) Increases
    (B) Decreases
    (C) Remain same
    (D) Increases linearly

5. During the constant rate period of drying of a solid,
    (A) Increased air humidity decreases the rate of drying
    (B) Increasing the air temperature decreases the drying rate
    (C) Surface evaporation of unbound moisture occurs
    (D) None of these

6. Large scale drying of wheat is done in a __________ dryer.
    (A) Fluidised bed
    (B) Spouted bed
    (C) Tray
    (D) Vacuum rotary

7. Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is
    (A) Insoluble in the liquid
    (B) Soluble in the liquid
    (C) Non-ideal in nature
    (D) At a fixed temperature

8. With increase in temperature, the leaching rate increases due to
    (A) Decreased liquid viscosity
    (B) Increased diffusivity
    (C) Both (a) and (b)
    (D) Neither (a) nor (b)

9. As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages
    (A) Increase
    (B) Decrease
    (C) Remain unchanged
    (D) Can either increase or decrease, depends on the system

10. In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed
    (A) q > 1
    (B) q < 1
    (C) q = 1
    (D) q = 0

11. Large scale drying of sugar is done in a __________ dryer.
    (A) Spouted bed
    (B) Tray
    (C) Rotary
    (D) Truck

12. Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysteresis. In such cases, the desorption equilibrium pressure is __________ that obtained for adsorption.
    (A) Lower than
    (B) Higher than
    (C) Same as
    (D) Either same or higher than

13. H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in meters) corresponding to an operating line given by, y = 5x + 0.001 is
    (A) 2.0
    (B) 1.56
    (C) 1.0
    (D) 0.56

14. Reboiler is considered as one theoretical plate, because
    (A) Of the assumption that vapour and liquid leaving the reboiler are in equilibrium
    (B) Vapour is recycled to the column
    (C) Reboiler itself contains one plate
    (D) None of these

15. In an absorption column, the flooding velocity for random packing is __________ that for stacked/regular packing.
    (A) Greater than
    (B) Smaller than
    (C) Equal to
    (D) Either (a), or (b); depends on the type of packing

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Item Reviewed: Chemical Mass Transfer MCQ Test - Set 01 Rating: 5 Reviewed By: Pranab Debnath
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