Principles of Mass Transfer Chemical Engineering MCQ - Set 26 - ObjectiveBooks

Principles of Mass Transfer Chemical Engineering MCQ - Set 26

Practice Test: Question Set - 26

1. If Rm is the minimum reflux ratio, the optimum reflux ratio may be around __________ Rm.
    (A) 1.2 to 1.5
    (B) 2.5 to 3
    (C) 3 to 4
    (D) 5

2. Adsorption is a unit operation which generally involves __________ systems.
    (A) Liquid-solid
    (B) Gas-solid
    (C) Fluid-solid
    (D) Solid-solid

3. Surface renewal model of mass transfer was enunciated by
    (A) Toor and Marcello
    (B) Fick
    (C) Danckwerts
    (D) Stefan

4. Agitator is provided in a crystallizer for
    (A) Avoiding deposition on cooler surfaces
    (B) Formation of nuclei
    (C) Crystal growth
    (D) All (a), (b) and (c)

5. Which of the following adsorbent is used to decolourise yellow glycerine?
    (A) Silica gel
    (B) Alumina
    (C) Fuller's earth
    (D) Activated carbon

6. Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of
    (A) Mass diffusivity to momentum diffusivity
    (B) Thermal diffusivity to mass diffusivity
    (C) Momentum diffusivity to thermal diffusivity
    (D) None of these

7. Binary distillation involves the mass transfer by __________ at the gas-liquid interface.
    (A) Unidirectional diffusion from liquid to gas phase
    (B) Unidirectional diffusion from gas to liquid phase
    (C) Either 'a' or 'b'
    (D) A counter diffusion at an almost equal molar rate

8. Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number.
    (A) Sherwood
    (B) Schmidt
    (C) Peclet
    (D) Stanton

9. Sand is dried in foundries in a _________drier.
    (A) Rotary
    (B) Fluidized bed
    (C) Vacuum
    (D) Spray

10. Cox chart is useful in the design of
    (A) Distillation column
    (B) Evaporator
    (C) Dryer
    (D) Crystallizer

11. Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are:
    (A) 4
    (B) 8
    (C) 9
    (D) 10

12. The binary diffusivity in gases and liquids vary respectively as
    (A) T3/2 and T
    (B) T and T3/2
    (C) √T and T3/2
    (D) T3/2 and √T

13. In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer.
    (A) The entire amount of C is transferred to solvent B
    (B) Less than 2 kg but more than 1 kg of C is transferred to solvent B
    (C) Less than 1 kg of C is transferred to B
    (D) No amount of C is transferred to B

14. Pick out the wrong statement pertaining to leaching.
    (A) Fine solids cannot be leached in a Pachuca tank
    (B) Door classifier can be used for leaching of coarse solids
    (C) Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor
    (D) Very high temperature is not needed for the leaching of sugar beet

15. Azeotropism for ethyl alcohol-water system disappears by
    (A) Increasing temperature
    (B) Decreasing pressure
    (C) Increasing pressure
    (D) No means

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