Practice Test: Question Set - 02
1. Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 × 10-3 kg mole/m2.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m2 .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is:
- (A) 5.6 × 10-4
- (B) 8.5 × 10-4
- (C) 5.6 × 10-3
- (D) 8.5 × 10-3
2. In case of cooling towers, the ratio of the rates of heat and mass transfer is indicated by the __________ number.
- (A) Lewis
- (B) Grashoff
- (C) Sherwood
- (D) None of these
3. When the gas to be dissolved in liquid is a/an __________ then normally co-current adsorber are used.
- (A) Mixture
of two gases
- (B) Pure
gas
- (C) Ideal
gas
- (D) Sparingly
soluble gas
4. Unsaturated air (with dry and wet bulb temperatures being 35 and 25°C respectively) is passed through water spray chamber maintained at 35°C. The air will be
- (A) Cooled
- (B) Humidified
- (C) Both (a) & (b)
- (D) Dehumidified
5. __________ equation applies to diffusivities in liquids.
- (A) Gilliland
- (B) Hirschfelder
- (C) Wilke and Chang
- (D) None of these
6. Mass transfer co-efficient is defined as
- (A) Flux =
Co-efficient/concentration difference
- (B) Co-efficient =
Flux/concentration difference
- (C) Flux=concentration
difference/coefficient
- (D) None of these
7. The relative volatility of a binary mixture at constant temperature __________ the total pressure.
- (A) Decreases
with increase in
- (B) Increases with
increase in
- (C) Is independent of
- (D) None of these
8. Large quantity of silica gel is normally dried in a __________ dryer.
- (A) Freeze
- (B) Through
circulation
- (C) Rotary
vacuum
- (D) Tray
9. The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which ‘D’ is the diffusivity of solute, is
- (A) D/a
- (B) D/2a
- (C) Proportional
to √D
- (D) Dependent on the
Reynolds number
10. The value of ‘L/mG’ ratio for economical absorption operation ranges from
- (A) 0.5 to 0.8
- (B) 0.8 to 1.2
- (C) 1.25 to 2.0
- (D) 2.5 to 3.5
11. Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature).
- (A) log P vs. T
- (B) log P vs.
log T
- (C) T vs. P
- (D) P vs. log T
12. In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction xf = 0.2. The mixture splits into an extract phase E and a raffinate phase R containing A at xB = 0.5 and xR = 0.05 respectively. The total mass of the extract phase is (in Kg)
- (A) 6.89
- (B) 8.89
- (C) 10
- (D) 8.25
13. The commonly used solvent in supercritical extraction is
- (A) Methyl
ethyl ketone
- (B) Water
- (C) Carbon
tetrachloride
- (D) Carbon
dioxide
14. Dried finished product sampled from various parts of a __________ dryer exhibits non-uniformity in the moisture content.
- (A) Rotary
- (B) Tray
- (C) Freeze
- (D) None of these
15. For the same system, if the same liquid used in an absorber is decreased, the tower height will
- (A) Increase
- (B) Decrease
- (C) Remain
unaffected
- (D) Decrease or increase;
depends on the type of liquid
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