chemical engineering MCQs – Page 105

Practise multiple-choice questions from chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering Mcqs

2081. In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of_______________________?
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A. Tower cross-section

B. Area between operating line and 45 diagonal x-y diagram

C. Condenser and reboiler surfaces

D. None of these

2082. Lewis number, which is important in problems involving simultaneous heat and mass transfer, is the ratio of__________________?
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A. Momentum diffusivity to thermal diffusivity

B. Mass diffusivity to momentum diffusivity

C. None of these

D. Thermal diffusivity to mass diffusivity

2083. JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by___________________?
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A. Nsc = 2

B. Nst = 2

C. Nsh = 2

D. None of these

2084. Which of the following adsorbent is used in the refining of sugar?
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A. Silica gel

B. Bone charcoal

C. Wood charcoal

D. Activated clay

2085. Smoke is an example of ___________________?
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A. Solid dispersed in liquid

B. Gas dispersed in liquid

C. Solid dispersed in gas

D. Liquid dispersed in gas

2086. Mass transfer rate between two fluid phases does not necessarily depend on the ______________ of the two phases?
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A. Degree of turbulence

B. Chemical properties

C. Physical properties

D. Interfacial area

2087. Inside the distillation columns, the ________________________?
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A. Highest temperatures is near the feed plate

B. Vapors are not always at their dew points

C. All A., B. and C.

D. Driving force for the liquid flow is its weight

2088. Extraction of coffee from its seed is done by___________________?
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A. Steam distillation

B. Liquid-liquid extraction

C. Extractive distillation

D. Leaching

2089. Inside the distillation column, the________________________?
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A. Pressure increases gradually from bottom to the top of the column

B. None of these

C. Liquids are not always at their bubble points

D. Driving force for the vapour flow is the pressure drop

2090. A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process ?
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A. Relative humidity of outlet air

B. Humidity of inlet air

C. Flow rate of inlet air

D. Temperature of the solid

2091. The rate of solid-liquid extraction is limited by the_________________?
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A. ution

B. Diffusion of the solute from the solution in contact with the particle to the main bulk of the

C. Phase change of the solute as it dissolves in the solvent

D. Diffusion of the solute through the solvent in the pores to the outside of the particle

E. All A , B. & C.

2092. To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate) ____________________?
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A. Increase both G and S

B. Decrease both G and S

C. Increase S and decrease G

D. Increase G and decrease S

2093. Pick out the wrong statement?
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A. erally

B. In case of a packed tower, the operating velocity is about half of the flooding velocity,

C. Change in barometric pressure does not affect the relative humidity

D. The equilibrium moisture content of the solid can be reduced by increasing the absolute

E. idity</strong>

F. Elution means the desorption of the adsorbed solute by a solvent

2094. Absorption accompanied with chemical reaction is exemplified by the absorption of___________________?
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A. Benzol present in coke oven gas by wash oil

B. SO2 in alkaline solution

C. All A., B. and C.

D. Ammonia in water

2095. Dew point of a gas-vapour mixture_____________________?
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A. Decreases with decrease in pressure

B. Increases with temperature rise

C. Increases with increase in pressure

D. Decreases with temperature rise

2096. Stacked packing compared to dumped packing_________________?
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A. Provides poorer contact between the fluids

B. Gives lower pressure drop

C. Both A. and B.

D. Gives higher pressure drop

2097. Separation of a mixture of two gases by absorption in the liquid solvent depends upon the difference in their____________________?
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A. Viscosity

B. Density

C. Solubility

D. Relative volatility

2098. The relative humidity of air decreases in-spite of an increase in the absolute humidity, when the____________________?
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A. Pressure falls

B. Temperature rises

C. Temperature falls

D. Pressure rises

2099. Below is given an equilibrium moisture curve of a substance. State which regions represent free moisture and unbound moisture respectively ?
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A. II, IV

B. II, III

C. IV, II

D. IV, III

2100. Pick out the correct statement?
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A. The driving force for mass transfer in a wet solid is its free moisture content

B. Bound moisture is removed during constant rate drying period

C. Free moisture is removed during falling rate drying period

D. The sum of free moisture and equilibrium moisture in a solid is called the critical moisture

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