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Home » Engineering » Chemical Engineering » Aptitude Test - 30
1.For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG: mass transfer co-efficient, moles/m2, a: interfacial area per unit volume of tower) ?
A. G/(FG . a)
B. FG/(G . a)
C. (G . a)/FG
D. G/(FG . a)
2.Pore size of the molecular sieve 5A is ___ mm ?
A. 5
B. 0.5
C. 0.05
D. 5
3.To remove all the moisture from a wet solid it requires exposure to ____ air?
A. Perfectly dry
B. Highly humid
C. High temperature
D. Perfectly dry
4.The cooling effect in a cooling tower can be speeded up by ____?
A. Increasing the air velocity and area of exposed wet surface
B. Reducing the barometric pressure
C. Reducing the humidity of the air
D. Increasing the air velocity and area of exposed wet surface
5.The Knudsen diffusivity is proportional to (where, T = absolute temperature)?
A. ?T
B. T2
C. T
D. ?T
6.A natural draft cooling tower is filled with wooden grids, which covers about ____ percent of the tower height?
A. 15-Oct
B. 30-40
C. 70-80
D. 15-Oct
7.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
8.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. Increases
9.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. Free
10.For absorbing a sparingly soluble gas in a liquid, the___?
A. Gas side co-efficient should be increased
B. Liquid side coefficient should be increased
C. Gas side co-efficient should be decreased
D. Gas side co-efficient should be increased
11.The relative volatility of a binary mixture at the Azeotropic composition is?
A. 1-Jan
B. > 1
C. 0
D. 1-Jan
12.Penetration theory states that the mass transfer co-coefficient is equal to (where, De is diffusivity and �t� is time) ?
A. (De.t)1/2
B. (De/t)1/2
C. (4De/?t)1/2
D. (De.t)1/2
13.The equation, NA = (DAB . Pt /RTZ) (y1 � y2) is for ____?
A. Steady state equimolar counter diffusion
B. Fick�s first law of diffusion
C. Steady state diffusion for stagnant case
D. Steady state equimolar counter diffusion
14.Coffee is prepared from coffee beans by leaching with___?
A. Cold water
B. Hot water
C. Dilute hot caustic solution
D. Cold water
15.Which of the following parameters remains constant during chemical dehumidification ?
A. Dry bulb temperature
B. Partial pressure of vapour
C. Wet bulb temperature
D. Dry bulb temperature
16.A slurry is to be dried to produce flaky solid. Which dryer would you recommend ?
A. Spray dryer
B. Drum dryer
C. Rotary dryer
D. Spray dryer
17.In steam distillation, the __?
A. Temperature is 100�C
B. Temperature is more than 100� C
C. Product must be immiscible with water
D. Temperature is 100�C
18.Dried finished product sampled from various parts of a ____ dryer exhibits nonuniformity in the moisture content?
A. Rotary
B. Tray
C. Freeze
D. Rotary
19.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. 0.5 to 0.8
20.Large quantity of silica gel is normally dried in a __ dryer?
A. Freeze
B. Through circulation
C. Rotary vacuum
D. Freeze
21.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. Flux = Co-efficient/concentration difference
22.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. Dehumidified
D. Cooled
23.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. Lewis
24.In an absorption column, the flooding velocity for random packing is ____ that for stacked/regular packing?
A. Greater than
B. Smaller than
C. Equal to
D. Greater than
25.In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed___?
A. q > 1
B. q < 1
C. q = 1
D. q > 1
26.With increase in temperature, the leaching rate increases due to___?
A. Decreased liquid viscosity
B. Increased diffusivity
C. Both A. and B.
D. Decreased liquid viscosity
27.Large scale drying of wheat is done in a _____ dryer?
A. Fluidised bed
B. Spouted bed
C. Tray
D. Fluidised bed
28.With increase in the mass velocity of the gas, the rate of drying during the constant rate period ______________, if the conduction and radiation through the solid are negligible ?
A. Increases
B. Decreases
C. Remain same
D. Increases
29.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. Flow rate of the entering gas
30.Molecular sieves are regenerated by heating to ____ �C?
A. < 150
B. 200-330
C. > 500
D. < 150
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