Practice Test: Question Set - 04
1. The Knudsen diffusivity is proportional to (where, T = absolute temperature)
- (A) √T
- (B) T2
- (C) T
- (D) T4
2. Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture.
- (A) Free
- (B) Unbound
- (C) Equilibrium
- (D) Bound
3. For the flow of gases through a capillary, with increase in temperature, the permeability __________ as per Knudsen law.
- (A) Increases
- (B) Decreases
- (C) Remain same
- (D) Either (a) or (b);
depends on the gas
4. A natural draft cooling tower is filled with wooden grids, which covers about __________ percent of the tower height.
- (A) 10-15
- (B) 30-40
- (C) 70-80
- (D) 90-100
5. With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop
- (A) Decreases
- (B) Remains
unchanged
- (C) Increases
- (D) Decreases
exponentially
6. Which of the following is not fixed by the process requirements, in the design of absorbers?
- (A) Flow
rate of the entering gas
- (B) Composition
of the entering liquid
- (C) Terminal
concentrations of gas stream
- (D) None
of these
7. Pick out the wrong statement:
- (A) Absorption factor is
constant, when the equilibrium and operating lines are straight
- (B) In case of a
stripper, the equilibrium curve is always below the operating line
- (C) In case of an
absorber, the operating line is always above the equilibrium curve
- (D) In the absorption of
low solubility gases, the liquid film is the controlling resistance
8. Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C?
- (A) Humidification only
- (B) Heating only
- (C) Both heating and
humidification
- (D) Evaporative cooling
9. The velocity, concentration and temperature boundary, for the boundary layer development on a flat plate during connective mass transfer will be same, if
- (A) NSc = 1
- (B) NSc = NPr = NLe
- (C) NPr = NLe
- (D) NSc = NLe
10. Pick out the wrong statement. Generally for physical adsorption, a gas of
- (A) Higher molecular
weight is adsorbed in preference to a gas of low molecular weight
- (B) High
critical temperature is adsorbed in preference to a gas of low critical
temperature
- (C) Low volatility is
adsorbed in preference to a gas of high volatility
- (D) None of these
11. Co-current absorbers are usually used when the gas to be dissolved in the liquid is
- (A) Sparingly soluble
- (B) Highly soluble
- (C) A pure substance
- (D) A mixture
12. Molecular sieves are regenerated by heating to __________ °C.
- (A) <
150
- (B) 200-330
- (C) >
500
- (D) >
1000
13. In triangular co-ordinates, the ternary composition point falls __________ of the triangle.
- (A) In the corners
- (B) Inside
- (C) On the sides
- (D) None of these
14. When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,
- (A) As the acetone
concentration increases, the solubility curves approach each other
- (B) Both the phases
become identical at a particular common point on both the solubility curves
called the plait point
- (C) The distribution
curve which is a plot between x (acetone concentration in one phase) and y
(acetone concentration in other phase) is analogous to x-y curve used in
distillation and absorption terminates on the x = y diagonal at the
concentration of the plait point
- (D) All (a), (b) and (c)
15. During sensible cooling process
- (A) Relative humidity
decreases
- (B) Relative humidity
increases
- (C) Wet bulb temperature
decreases
- (D) Both (b) and (c)
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