Mass Transfer Solved Questions and Answers - Set 23 - ObjectiveBooks

Mass Transfer Solved Questions and Answers - Set 23

Practice Test: Question Set - 23


1. Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture.
    (A) Unbound
    (B) Free
    (C) Critical
    (D) Bound

2. Which of the following is an undesirable characteristic for the solvent used in gas absorption?
    (A) Low vapor pressure
    (B) Low viscosity
    (C) High gas solubility
    (D) None of these

3. Hypersorption refers to a __________ process.
    (A) Fixed bed absorption
    (B) Moving bed absorption
    (C) Fixed bed adsorption
    (D) Moving bed adsorption

4. Drying of refractory is normally carried out in a __________ dryer.
    (A) Open pan
    (B) Tray
    (C) Rotary vacuum
    (D) Truck/tunnel

5. For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will
    (A) Increase
    (B) Decrease
    (C) Remain same
    (D) Data insufficient, can't be predicted

6. In case of liquids, the binary diffusivity is proportional to (where, T = temperature)
    (A) T
    (B) √T
    (C) T2
    (D) 1/T

7. A liquid mixture contains 30% o-xylene, 60% p-xylene and 10%. m-xylene (all percentages in w/w). Which of the following statements would be true in respect of this mixture?
    (A) The mixture exhibits an azeotrope at 101.3 kPa
    (B) The composition of the mixture, in percent by volume is: o-xylene 30, p-xylene 60. and m-xylene 10
    (C) The composition of the mixture in mole percent is: o-xylene 30, p-xylene 60 and m-xyoene 10
    (D) The mixture contain optical isomers

8. The relative saturation of an unsaturated mixture of gas and vapor is independent of the
    (A) Nature of the vapor
    (B) Temperature of the mixture
    (C) Composition of the mixture
    (D) None of these

9. In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of
    (A) Area between operating line and 45° diagonal x-y diagram
    (B) Condenser and reboiler surfaces
    (C) Tower cross-section
    (D) None of these

10. Advantage of continuous drying over batch drying is that the
    (A) Drying cost per unit weight of dried product is less
    (B) Product with more uniform moisture content is produced
    (C) Equipment size required is smaller
    (D) All 'a', 'b' & 'c'

11. Which of the following assumes constant molal vaporization and overflow?
    (A) McCabe-Thiele method
    (B) Ponchan-Savarit method
    (C) Enthalpy concentration method
    (D) Plate absorption column

12. An air-water vapor mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapor pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapor/kg of dry air is:
    (A) 0.048
    (B) 0.079
    (C) 0.122
    (D) 0.152

13. Which of the following binary systems is an example of a maximum boiling azeotrope?
    (A) Water-hydrochloric acid
    (B) Acetone-carbon disulphide
    (C) Water-ethyl alcohol
    (D) n-heptane-n-octane

14. For an absorber, both equilibrium and operating line will be straight for
    (A) Concentrated solution and non-isothermal operation
    (B) Dilute solution and non-isothermal operation
    (C) Dilute solution and isothermal operation
    (D) Concentrated solution and isothermal operation

15. Channelling is most severe
    (A) In towers packed with stacked packing
    (B) In towers packed randomly with crushed solids
    (C) In dumped packing of regular units
    (D) At very high liquid flow rate

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