Mass Transfer - Chemical Engineering Objective Type Questions - Set 34 - ObjectiveBooks

Mass Transfer - Chemical Engineering Objective Type Questions - Set 34

Practice Test: Question Set - 34


1. Pick out the wrong statement:
    (A) Reboiler is not used in open steam distillation
    (B) The separation of solutes of different molecular sizes in a liquid solution by use of a suitable membrane is called dialysis
    (C) Freeze drying is used for the drying of fish
    (D) Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition

2. In an operating distillation column, the
    (A) Vapors and liquids are at their dew point and bubble point respectively
    (B) Driving force for the liquid flow is its specific weight
    (C) Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column
    (D) Highest temperature is encountered at the top of the column

3. Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre.
    (A) Electrical resistance
    (B) Thermal conductivity
    (C) Strength
    (D) None of these

4. As per Gilliland's equation, the diffusivity is
    (A) Directly proportional to 'T1.5'
    (B) Inversely proportional to 'P'
    (C) Dependent on the molecular volume & molecular weight of components
    (D) All 'a', 'b' & 'c'

5. Pick out the wrong statement.
    (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapor feed
    (B) In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency
    (C) For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 × 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10-2m/s
    (D) The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity

6. If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that
    (A) The system comprises of partially miscible liquids
    (B) The system comprises of miscible liquids
    (C) The system comprises of an azeotrope
    (D) On heating, a vapor phase will appear; while on cooling, a solid phase will appear

7. Leaching of coffee from coffee beans is done by
    (A) Hot water
    (B) Hexane
    (C) Lime water
    (D) Dilute H2SO4 (hot)

8. In case of an absorber, the operating
    (A) Line always lies above the equilibrium curve
    (B) Line always lies below the equilibrium curve
    (C) Line can be either above or below the equilibrium curve
    (D) Velocity is more than the loading velocity

9. Desirable value of absorption factor in an absorber is
    (A) 1
    (B) < 1
    (C) > 1
    (D) 0.5

10. Radioactive nuclear waste is treated in
    (A) Mixer-settler extractor
    (B) Rotating-disc contactor
    (C) Pulsed column extractor
    (D) Bollman extractor

11. In case of a desorber (stripper), the
    (A) Operating line always lies above the equilibrium curve
    (B) Operating line always lies below the equilibrium curve
    (C) Temperature remains unaffected
    (D) Temperature always increases

12. In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit).
    (A) Straight
    (B) Parallel
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

13. Make up water is required in a cooling tower to replace the water lost by
    (A) Evaporation
    (B) Drift
    (C) Blowdown and leakage
    (D) All (a), (b) and (c)

14. Langmuir equation is associated with
    (A) Leaching
    (B) Adsorption
    (C) Steam distillation
    (D) Multi-component absorption

15. A packed tower compared to a plate tower for a particular mass transfer operation
    (A) Incurs smaller pressure drop
    (B) Allows installation of cooling coils
    (C) Is less costly when built in large sizes/diameters
    (D) Is more suitable, if suspended solids are present in fluid streams

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