chemical engineering Mcqs
1751. Dorr thickener is an equipment used for___________________?
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A. Classification

B. Clarification

C. Leaching

D. Sedimentation
1752. Pick out the wrong statement ?
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A. Acid resistant cements are known as silicate cement

B. High early strength cement are made from materials having high silica to lime ratio

C. Major component of greyish Portland cement is tricalcium silicate

D. The function of gypsum in cement is to enhance its initial setting rate

1753. The equipment used in the extraction of highly corrosive radioactive liquids is_______________________?
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A. Spray column

B. Baffle tower

C. Mixer settler

D. Pulse column
1754. Pick out the wrong statement ?
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A. Mechanical agitation is required, if the system has low interfacial tension

B. Sieve tray towers are generally used for systems having low interfacial tension

C. When Henrys law constant is very small, then the mass transfer rate is controlled by the gas

D. m resistance

E. Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar

F. turbulent layers

1755. For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottom product streams__________________?
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A. Decreases

B. Increases

C. Remain unaffected

D. Passes through a maximum

1756. All moisture in a non-hygroscopic material is the ________________ moisture?
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A. Unbound

B. Bound

C. Equilibrium

D. Free

1757. The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force) ?
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A. Kc = Kp/RT = Km . RT/P

B. Kc = Kp = Km

C. Kc = Kp . RT = Km . RT/p

D. None of these

1758. In stripping section of continuous distillation column, the_______________________?
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A. Vapour is stripped of low boiler

B. Liquid is stripped of high boiler

C. None of these

D. Liquid is enriched with high boiler
1759. Steam distillation is not recommended to be used, if the _____________________?
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A. ponents associated with it, at the boiling temperature

B. Material to be distilled is thermally unstable or has the tendency to react with other

C. ling temperature

D. Liquids decompose, if distilled directly at atmospheric pressure

E. Azeotropic mixture is to be separated and the final product is miscible with water

F. Material cannot be distilled by indirect heating even under low pressure, because of the high

1760. In a distillation column, with increase in the reflux ratio, the heat removed in the cooler ______________________?
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A. Decreases

B. Remains unaffected

C. And the heat required in reboiler decreases

D. Increases
1761. With increase in temperature, the mutual solubility of two liquids_________________?
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A. Decreases exponentially

B. Decreases

C. Increases

D. Remains unchanged

1762. Experimental determination of _______________ is done by wetted wall column method?
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A. NTU

B. Diffusion co-efficient

C. Mass transfer co-efficient

D. None of these

1763. Pick out the wrong statement ?
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A. nomy

B. Decrease in Murphree plate efficiency is an indication of entrainment in distillation column

C. The capacity of a distillation column is maximum at total reflux

D. In solvent extraction, the distribution co-efficient should be as large as possible for solvent

E. With increase in pressure, the solubility of gases in solvent increases at a fixed temperature

1764. Mass transfer co-efficient is directly proportional to DAB 0.5, according to ________________ theory ?
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A. Penetration

B. Film

C. None of these

D. Surface renewal

1765. Which of the following is an undesirable property in a tower packing ?
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A. Large surface per unit volume

B. Large free cross-section

C. Large weight of liquid retained

D. Low weight per unit volume

1766. Tower diameter may be decreased by__________________?
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A. Use of increased tray spacing

B. Increasing the liquid flow rate

C. Using higher reflux ratio

D. Increasing the vapour flow rate

1767. Components, having widely different boiling point in a binary mixture, can be separated using ________________ distillation?
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A. Extractive

B. Simple

C. Molecular

D. Steam

1768. ADDUCTS and CLATHRATES are used in case of_____________________?
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A. Absorption

B. Crystallisation

C. None of these

D. Extractive distillation

1769. Back-trapping in a distillation column ?
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A. Is desirable, as it provides improved vapour-liquid contact

B. Reduces pressure drop

C. Increases tray efficiency

D. Decreases tray efficiency
1770. Pick out the wrong statement pertaining to the cooling towers ?
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A. Effectiveness of forced draft cooling tower is reduced by the recirculation of the humid and

B. discharged air

C. Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb

D. perature is also low

E. In case of induced draft cooling tower, the fan is placed at the top of the tower

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

1771. A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below: In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is_______________ ?
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A. 0.6

B. 0.5

C. 2

D. 1

1772. Humid volume is the total volume in m3 of 1 kg of _____________________?
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A. Gas plus its accompanying vapour at 1 atm. and gas temperature

B. Gas plus its accompanying vapour at 1 atm. and room temperature

C. Vapour laden gas at 1 atm. and gas temperature

D. Vapour laden gas at 1 atm. and room temperature

1773. During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the _________________ remains constant ?
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A. Wet bulb temperature

B. Partial pressure of water vapor

C. Relative humidity

D. None of these

1774. In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is__________________?
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A. Equal to the heat of formation of surface compound

B. Called integral heat of adsorption

C. Zero

D. Equal to the heat of wetting
1775. Decoction refers to the use of solvent________________?
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A. None of these

B. At its boiling point

C. At ambient temperature

D. In its vapor form

1776. Flooding in a distillation column is detected by a sharp ___________________?
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A. Decrease in pressure drop

B. Increase in Murphree plate efficiency

C. Increase in pressure drop

D. Decrease in liquid hold up in the column

1777. Which of the following equipments is not used for liquid dispersion ?
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A. Packed towers

B. Venturi scrubbers

C. Agitated vessels

D. Wetted wall towers

1778. Plate efficiency in a distillation column is reduced due to the ______________________ of liquid?
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A. Weeping & dumping

B. Foaming

C. Entrainment

D. All A., B. & C.
1779. Flash distillation is suitable for separating the constituents of a binary system, which _____________________?
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A. Form minimum boiling azeotrope

B. Have very wide boiling points

C. Have very close boiling points

D. Form constant boiling azeotrope

1780. McCabe-Thiele method________________?
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A. Uses weight fractions to express liquid and vapour composition

B. Uses molal units for material and energy balance

C. Can use any type of units

D. Is more accurate than Ponchon-Savarit method

1781. The most efficient cooling tower out of the following is_____________________?
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A. Induced draft

B. Natural draft

C. Forced draft

D. Atmospheric

1782. Compound A is extracted from a solution of A + B into a pure solvent S. A Co-current unit is used for the liquid-liquid extraction. The inlet rate of the solution containing A is 200 moles of B/hr.m2 and the solvent flow, rate is 400 moles of S/m2. hr. The equilibrium data is represented by Y = 3X2 , where Y is in moles of a A/moles of B and X is in moles A/moles of S. The maximum percentage extraction achieved in the unit is_________________________?
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A. 90%

B. 50%

C. 70%

D. 25%

1783. Laboratory determination of the diffusivity of vapor is done by __________________ method?
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A. Wikes

B. Wetted wall column

C. Winkelmanns

D. Gillilands

1784. If the specific heats of a gas and a vapor are 0.2KJ/Kg.K and 1.5 KJ/Kg.K respectively, and the humidity is 0.01; the humid heat in KJ/Kg. is________________?
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A. 0.31

B. 0.017

C. 0.107

D. 0.215
1785. The value of NA/(NA + NB), for steady state equimolal counter diffusion of two gases A and B is____________?
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A. 2

B. 1

C. 0.5

D. ?
1786. In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be_____________________?
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A. At ground level

B. 2 metres above the ground

C. 5 metres above ground

D. 10 metres above ground

1787. A binary mixture of benzene and cyclohexane is separated by___________________?
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A. Flash vaporisation

B. Extractive distillation

C. Solvent extraction

D. Ordinary distillation

1788. In Azeotropic mixture, the equilibrium vapour composition is____________________?
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A. More than liquid composition

B. Less than liquid composition

C. Independent of pressure

D. Same as liquid composition
1789. Free flowing granular materials can be best dried in a __________________ drier?
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A. Drum

B. Rotary

C. Freeze

D. Cylinder

1790. The drying time between fixed moisture content within diffusion controlled falling rate period is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid) ?
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A. T

B. T3

C. T2

D. ?T

1791. Which of the following adsorbent is used to decolourise yellow glycerine ?
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A. Alumina

B. Fullers earth

C. Activated carbon

D. Silica gel

1792. Paper industry employs _______________ driers?
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A. Fluidised bed

B. Cylinder

C. Rotary

D. Spray

1793. For a distillation column operating at minimum reflux, the_______________________?
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A. Number of plates required will be maximum

B. None of these

C. Reflux ratio will be maximum

D. Concentration of liquid and vapour leaving a plate will be same

1794. A coalescer in a mixer-settler liquid-liquid extraction column______________________?
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A. Helps in increasing the bubble size entering the settler

B. All a, b, & c

C. Comprises of thin bed of substances of extended surface having high porosity

D. Helps in increasing the settling rate of the bubbles

1795. Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if____________________?
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A. There is equimolar counter diffusion

B. Diffusion of A is in stagnant medium B

C. Mass transfer is accompanied by reaction

D. Molecular mean free path is high

1796. Pick out the wrong statement ?
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A. Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure

B. stance

C. In case of gas absorption, HETP is equal to HTU, when both the operating line & the

D. ilibrium lines are parallel

E. Hatta number is important in case of gas absorption with chemical reaction

F. In actual practice, absorption is an endothermic process, while stripping is an exothermic
1797. Dew point of an air-water vapor mixture_________________?
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A. nt parallel to the temperature axis and to the saturation curve

B. At constant humidity & total pressure is fixed

C. All A , B. & C.

D. Corresponding to any point on the humidity chart is obtained by projecting a line through this

E. Decreases with decrease in pressure

1798. The individual mass transfer co-efficients (moles/m2s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling ?
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A. Liquid side

B. Gas side

C. Interfacial

D. Both liquid and gas side

1799. A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids))_____________?
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A. M ln(Xo/XF)

B. MXo ln(Xo/XF)

C. M(Xo/XF)

D. M(Xo XF)

1800. Pick out the wrong statement. Raoults law does not apply, when the______________________?
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A. Size of component molecules are not equal

B. mation of solution

C. Attractive forces between like and unlike molecules in the solution are approximately equal

D. Component molecules are non-polar

E. Chemical combination or molecular association between unlike molecules takes place in the