chemical engineering Mcqs
2001. Pick out the wrong statement?
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A. The operating pressure in solvent extraction system should be below vapor pressures of all

B. The operating line always lies below the equilibrium solubility curve in case of a single

C. ponent stripper

D. The operating line always lies above the equilibrium solubility curve in case of a single

E. ponent absorber

F. ponents</strong>

2002. As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches ____________________?
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A. Zero

B. None of these

C. That of normal condensation

D. Integral heat of adsorption

2003. Absorption factor, for a fixed degree of absorption from a fixed amount of gas should be_________________?
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A. < 1

B. ? 1

C. > 1

D. 1

2004. With increase in the concentration of the adsorbate, the integral heat of adsorption____________________?
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A. May increase or decrease; depends on the type of adsorbate

B. Decreases

C. Increases

D. Remains unchanged

2005. Make up water is required in a cooling tower to replace the water lost by___________________?
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A. Evaporation

B. Drift

C. All A., B. and C.

D. Blowdown and leakage

2006. If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that___________________?
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A. On heating, a vapor phase will appear; while on cooling, a solid phase will appear

B. The system comprises of partially miscible liquids

C. The system comprises of an azeotrope

D. The system comprises of miscible liquids

2007. _______________ developed the film theory ?
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A. Higbie

B. Ergun

C. Levenspiel

D. Fick

2008. When the liquid phase and vapour phase of a binary system obeys Raoults and Daltons law respectively, the relative volatility is the ratio of________________________?
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A. Vapour pressure of component A to the partial pressure of A

B. Vapour pressure of component A to that of component B

C. Vapour pressure of component A to the total pressure

D. Partial pressure of component A to the total pressure

2009. Chemisorption (chemical adsorption) is_______________________?
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A. A reversible phenomenon

B. Characterised by adsorption of heat

C. An irreversible phenomenon

D. Same as Van der Waals adsorption

2010. Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the ________________ of a fibre ?
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A. Strength

B. Electrical resistance

C. Thermal conductivity

D. None of these

2011. Condensation of a vapour-gas mixture just begins, when (where, p = partial pressure of the vapour P = vapour pressure of the liquid) ?
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A. p << P

B. p >>P

C. p = P

D. p < P

2012. A minimum boiling azeotrope is exemplified by__________________________?
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A. Water-isobutyl alcohol

B. None of these

C. Acetone-carbon disulphide

D. Toluene-benzene

2013. Rotary dryers cannot handle _______________ materials ?
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A. Sticky

B. Granular

C. Free flowing

D. Dry

2014. A plait point is the point on the solubility curve, where the tie line reduces to a point. What is the number of plait point for a ternary system containing two pairs of partially miscible liquids ?
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A. 0

B. 3

C. 2

D. 1

2015. Heat sensitive materials with very high latent heat of vaporisation may be economically separated using__________________?
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A. Evaporation

B. Liquid extraction

C. Absorption

D. Distillation

2016. The rough value of diffusion co-efficient of water vapor into air at 25C may be about ______________ cm2/sec?
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A. 0.0025

B. 0.25

C. 1.25

D. 2.5

2017. In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit) ?
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A. Straight

B. Parallel

C. Both A. & B.

D. Neither A. nor B.

2018. As the reflux ratio in a distillation column is increased from the minimum, the______________________?
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A. Liquid flow increases while the vapor flow decreases for a system

B. Total cost first decreases and then increases

C. Slope of the operating line in stripping section decreases

D. Number of plates decreases very slowly first and then more and more rapidly

2019. Pick out the wrong statement ?
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A. Even a forced draft cooling tower cannot cool water below the wet bulb temperature

B. Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele

C. tillation column</strong>

D. hod of theoretical plate calculation for distillation column

E. Heat removal load on cooler remains constant, even with increase of the reflux ratio in a

F. Different solids have different equilibrium moisture curves

2020. Leaching of coffee from coffee beans is done by___________________?
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A. Hot water

B. Dilute H2SO4 (hot)

C. Lime water

D. Hexane

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

2041. An Azeotropic mixture is a ________________ mixture?
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A. Binary

B. None of these

C. Constant boiling point

D. Ternary

2042. Entrainer used in Azeotropic distillation should____________________?
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A. Have high viscosity to provide high tray efficiency

B. Form a low boiling azeotrope with one of the constituents of the mixture

C. Have high latent heat of vaporisation

D. Form a new azeotrope of low relative volatility with one of the constituents of the mixture

2043. Langmuir equation is associated with________________________?
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A. Steam distillation

B. Leaching

C. Multi-component absorption

D. Adsorption
2044. Radioactive nuclear waste is treated in____________________?
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A. Mixer-settler extractor

B. Pulsed column extractor

C. Bollman extractor

D. Rotating-disc contactor

2045. Pick out the correct statement?
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A. Diffusivity increases with increase in molecular weight

B. None of these

C. Diffusivity decreases with increase in temperature

D. Diffusivity increases with the size of the individual molecule

2046. In extractive distillation, solvent is_____________________?
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A. Added to alter the relative volatility of the mixture

B. Of high volatility

C. Of high viscosity to give high tray efficiency

D. Present in overhead stream

2047. In case of an absorber, the operating _______________?
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A. Line can be either above or below the equilibrium curve

B. Line always lies below the equilibrium curve

C. Line always lies above the equilibrium curve

D. Velocity is more than the loading velocity

2048. Which of the following solutions will follow Raoults law most closely ?
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A. 35% solution of camphor in water

B. A solution of polar organic compounds (not of homologue of a series)

C. 35% solution of NH3 in water

D. A solution of benzene, toluene and o-xylene
2049. Wetted wall tower experiment determines the__________________?
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A. Volumetric co-efficient

B. Molal diffusivity

C. None of these

D. Mass transfer co-efficient
2050. The diffusion co-efficient in m2/s. of acetic acid in benzene (liquid in liquid) is___________________?
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A. 2.09 10-5

B. 2.09 10-4

C. 2.09 10-12

D. 2.09 10-9