chemical engineering MCQs – Page 102

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 Review each marked answer and report any item that may be outdated or unclear.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

2021. Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when____________________?
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A. One of the liquid components has very high affinity towards the solvent

B. Extracting solvent is cheaply & abundantly available

C. One of the liquid components is heat sensitive

D. Viscosity of liquid components is very high

2022. At a fixed total pressure, humidity depends only on the _______________________?
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A. Heat capacity of the vapour

B. Density of the vapour

C. None of these

D. Partial pressure of vapour in the mixture

2023. With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux__________________?
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A. May increase or decrease; depends on system

B. Remain same

C. Increases

D. Decreases

2024. For the air water system under ambient conditions, the adiabatic saturation temperature and the wet bulb temperature are nearly equal, because__________________?
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A. Water has a high latent heat of evaporation

B. Lewis number is close to unity

C. Solubility of the components of air in water is very small

D. They are always equal under all circumstances

2025. During drying operation, it is easier to remove the ________________ moisture ?
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A. Critical

B. Unbound

C. Bound

D. Equilibrium

2026. Pick out the wrong statement?
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A. The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness,

B. uid feed and horizontal feed line represents saturated vapour feed

C. te is 2 10-2m/s</strong>

D. m the leading edge is 1.5 10-2m/s. Then the average mass transfer co-efficient for the

E. iciency is smaller than Murphree efficiency

F. In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated

2027. Pick out the wrong statement?
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A. Diameter of randomly packed tower is normally more than 1.2 metres

B. oding is generally encountered in packed towers

C. king is less and they (packings) also lessen the possibility of tower wall collapse

D. Packed towers are preferred over plate towers for handling corrosive and foamy liquids

E. Packed towers are preferred for vacuum operation, because the pressure drop through the

F. Due to uneven supply and improper distribution of liquid, problem of channelling, loading &

2028. Ponchon-Savarit method analyses the fractional equipment based on___________________?
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A. Enthalpy balance only

B. Material balance only

C. Both enthalpy and material balances

D. The assumption of constant molal-overflow

2029. A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state ?
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A. Composition of vapors and that of liquid do not vary throughout the column

B. The top and bottom compositions correspond to the maximum enrichment available

C. Reboiler load and condenser load are minimum

D. The top and bottom compositions are unchanged with and without total reflux

2030. With increase in solvent rate, the number of transfer units, NtoG, for a fixed degree of absorption from a fixed amount of gas________________?
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A. Decreases linearly

B. Remain unaffected

C. Increases

D. Decreases

2031. Pick out the correct statement ?
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A. Dialysis process is used for the production of fresh water from brine

B. Electrodialysis is used in the manufacture of NaOH

C. Electrodialysis is used for the refining/purification of petrol

D. Both B. and C.

2032. Relative humidity is the ratio of the______________________?
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A. Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature

B. Partial pressure of the vapour to the vapour pressure of the liquid at room temperature

C. Actual humidity to saturation humidity

D. None of these

2033. In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is_______________________?
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A. 0.6

B. 0.50

C. 2

D. 1

2034. In a forced draft cooling tower, water is cooled from 95 to 80F by exposure to air with a wet bulb temperature of 70F. In this case, the________________________?
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A. Range is 15F

B. Approach is 10F

C. Both A. & B.

D. Neither A. nor B.

2035. Pick out the wrong statement pertaining to the cooling towers ?
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A. Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb

B. A natural draft cooling tower is recommended to be used, when the air humidity is low and air

C. perature</strong>

D. perature is also low

E. discharged air

F. Effectiveness of forced draft cooling tower is reduced by the recirculation of the humid and

2036. Solvent used in extractive distillation_________________________?
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A. Forms a low boiling azeotrope

B. Does not alter the relative volatility of the original components

C. Is of low volatility

D. Forms a high boiling azeotrope

2037. Schmidt number is given by ___________________?
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A. Re/Pe

B. Re Pe

C. ?/?DAB

D. Sh Pe

2038. In paper industry, paper is dried in a _____________ dryer ?
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A. Tunnel

B. Conveyor

C. Festoon

D. Heated cylinder

2039. Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for_________________?
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A. All A., B. and C.

B. Constant relative volatility

C. Total reflux

D. Constant molal overflow

2040. A liquid mixture contains 30% o-xylene, 60% p-xylene and 10%. m-xylene (all percentages in w/w). Which of the following statements would be true in respect of this mixture ?
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A. The mixture contain optical isomers

B. The composition of the mixture in mole percent is: o-xylene 30, p-xylene 60 and m-xyoene 10

C. The mixture exhibits an azeotrope at 101.3 kPa

D. The composition of the mixture, in percent by volume is: o-xylene 30, p-xylene 60. and mxylene

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