chemical engineering Mcqs
2201. The film penetration model of mass transfer was enunciated by______________________?
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A. Gilliland

B. Fick

C. Toor and Marcello

D. Stefan

2202. Pick out the correct statement ?
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A. In case of liquid-liquid extraction, no separation is possible, if the selectivity of the solvent

B. All A., B. and C.

C. d is unity

D. With increase in temperature, the selectivity of the solvent used in solvent extraction

E. reases

F. The selectivity of solvent used in solvent extraction is unity at the plait point

2203. Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve) ____________________?
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A. S1 S2

B. S2/S1

C. S1 S2

D. S1/S2
2204. In distillation, overhead product contains ______________________?
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A. Only saturated liquid

B. Only one component

C. Any number of components

D. Two components

2205. Pick out the system with minimum boiling azeotrope at 1 atm ?
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A. Benzene-toluene

B. Ethyl alcohol-water

C. Hydrochloric acid-water

D. All A., B. and C.

2206. Minimum possible diameter of a packed column is decided mainly by the________________________?
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A. Liquid hold up

B. Liquid density

C. Gas viscosity

D. Flooding
2207. Channelling is most severe_____________________?
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A. In dumped packing of regular units

B. In towers packed with stacked packing

C. At very high liquid flow rate

D. In towers packed randomly with crushed solids

2208. Molarity is defined as the number of gm moles of solute per ________________ of solvent?
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A. kg

B. c.c

C. gm

D. Litre
2209. A mixture of 10% C6H6 vapour in air at 25C and 750 mm Hg has a dew point of 20C. Its dew point at 30C and 700 mm Hg will be around _______________ C?
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A. 27.3

B. 21.7

C. 20

D. 18.7
2210. If the amount of the steam used in steam distillation is increased, the temperature of distillation__________________?
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A. Decreases

B. Depends on relative volatility

C. Increases

D. Remains unchanged

2211. (NRe . NSc) is termed in mass transfer operation as the ______________ number?
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A. Peclet

B. Stanton

C. Sherwood

D. None of these

2212. On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in______________________?
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A. Greater degree of separation with a fixed number of trays

B. None of these

C. Increased reflux ratio

D. Increased reboiler load

2213. 1 kg of a saturated aqueous solution of a highly soluble component A at 60C is cooled to 25C. The solubility limits of A are (0.6 kgA/kg water) at 60C and (0.2 kgA/kg water) at 25C. The amount in kg of the crystals formed is________________________?
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A. 0.25

B. 0.175

C. 0.4

D. 0.2
2214. Which of the following is an undesirable characteristic for the solvent used in gas absorption ?
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A. Low viscosity

B. High gas solubility

C. None of these

D. Low vapor pressure

2215. At what value of reflux ratio, number of theoretical plates in a distillation column is minimum ?
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A. < 1

B. ?

C. 0

D. 1

2216. A packed tower compared to a plate tower for a particular mass transfer operation__________________?
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A. Allows installation of cooling coils

B. Incurs smaller pressure drop

C. Is less costly when built in large sizes/diameters

D. Is more suitable, if suspended solids are present in fluid streams

2217. Which of the following unit operations makes use of Thiele-Geddes equation ?
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A. Multi-component distillation

B. Multi-component absorption with chemical reaction

C. Liquid-liquid extraction

D. Solid-liquid extraction

2218. Relative volatility does not change appreciably with the change in_____________________?
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A. Total pressure

B. Vapour pressure of either component

C. None of these

D. Temperature
2219. In a moderately sized packed absorption tower, channelling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter ?
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A. > 8:1

B. < 6:1

C. < 8 : 1

D. > 4 :1

2220. The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = _________________?
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A. 1

B. 0.5

C. 0

D. 10

2221. For continuous drying of granular or crystalline material, the dryer used is the _______________ dryer?
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A. Tunnel

B. None of these

C. Rotary

D. Tray

2222. In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads? Reflux conditions: (i) Reflux stream is completely liquid and is at its bubble point. (ii) Reflux stream is below its bubble point ?
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A. Condenser and reboiler loads are the same in both the cases

B. Reboiler load is the same in both the cases but condenser load is higher in case (ii)

C. Condenser load is the same in both the cases but reboiler load is higher in case (ii)

D. Both condenser and reboiler loads are higher in case (ii) as compared to case (i)
2223. The diffusivity D. in a binary gas mixture is related to the temperature (T) as________________________?
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A. D ? T1.5

B. D ? T2

C. D ? T

D. D ? T0.5

2224. _____________ is used as an entrainer for the separation of acetic acid-water mixture by distillation?
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A. Benzol

B. Hexane

C. Furfural

D. Butyl acetate
2225. Molecular diffusion is caused by the________________?
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A. Potential energy of the molecules

B. Activation energy of the molecules

C. Transfer of molecules from low concentration to high concentration region

D. Thermal energy of the molecules
2226. The operating line for an absorber is curved, when plotted in terms of _______________________?
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A. Mass fractions

B. Partial pressure

C. Mole ratios

D. Mole fractions

2227. Which of the following mixtures does not form an azeotrope at atmospheric pressure ?
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A. Water-alcohol

B. Methyl alcohol-acetone

C. Butyl acetate-water

D. None of these
2228. If mass diffusivity in a mixture is equal to the thermal diffusivity, then the Lewis number is____________________
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A. 1

B. 0

C. 1
2229. Heat load in a cooling tower______________________?
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A. Means the amount of heat thrown away (KCal/hr.) by the cooling tower

B. Is equal to the number of kg, of water circulated times the cooling range

C. Both A. & B.

D. Neither A. nor B.

2230. Which of the following is an undesirable property for an absorbing solvent ?
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A. Low freezing point

B. None of these

C. Low vapour pressure

D. Low velocity

2231. In case of gases, the binary diffusivity is proportional to (where, P = pressure) ?
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A. ?P

B. 1/?P

C. P

D. 1/P
2232. Diffusion in concentrated solutions differs from that in dilute solutions, because of the change in the _______________ with the concentration of the solution?
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A. Degree of ideality

B. Viscosity

C. Both A & B

D. Neither A nor B

2233. Calcium ammonium nitrate (a fertiliser) is dried in a _________________ dryer?
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A. Tunnel

B. Rotary

C. Vacuum

D. Tray

2234. The rate of mass transfer is not dependent upon the______________________?
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A. Degree of dispersion of one fluid in the other

B. Interfacial surface exposed between the phases

C. Both A. & B.

D. None of these
2235. Which of the following is the most suitable for extraction in a system having very low density difference ?
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A. strong>. Pulsed extractor

B. Mixer-settler extractor

C. Centrifugal extractor

D. Packed extraction tower

2236. In distillation columns, the number of bubble caps per tray primarily depends upon the_______________________?
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A. Allowable gas velocity

B. Allowable liquid velocity

C. Feed composition

D. Allowable gas and liquid velocities
2237. Channelling in a packed tower results from the_____________________?
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A. High pressure drop

B. Maldistribution of liquid

C. Non-uniformity of packing

D. Both B. and C.
2238. Pick out the wrong statement pertaining to the rotary dryer ?
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A. instant. The best performance for rotary drier is obtained, when the hold up is in the range

B. Recommended peripheral speed of a rotary drier is in the range of 10 to 30 metres/minute

C. Hold up of a rotary drier is defined as the fraction of the dryer volume occupied by the solid at

D. n through the current of hot air/gases. It extends from the wall to a distance which is about

E. Flights (located in the inside shell of rotary dryer) lift the material being dried and shower it

F. Rotary dryer is suitable for drying sticky material
2239. For turbulent mass transfer in pipes, the Sherwood number depends on the Reynolds number as___________________?
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A. Re0.53

B. Re

C. Re0.33

D. Re0.83
2240. Which of the following employs an accessory known as drift eliminator ?
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A. Multiple effect evaporator

B. Rotary dryer

C. Mechanical draft cooling tower

D. Rotating disc contactor

2241. When adsorption hysteresis is observed, the desorption equilibrium pressure is _________________ that obtained by adsorption?
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A. Same as

B. Dependent on the system; can be either lower or higher than

C. Always higher than

D. Always lower than
2242. The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called__________________?
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A. Elutriation or elution

B. Decoction

C. Percolation

D. None of these

2243. If the overall efficiency and Murphree plate efficiency are equal, then both the equilibrium and operating lines are_______________?
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A. Straight

B. Parallel

C. Both A. & B.

D. Neither A. nor B.

2244. Flooding in a vapor-liquid contacting equipment occurs in a tray, when the pressure drop through a tray is _______________ the liquid head available in the downcomer?
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A. Same as

B. More than

C. Less than

D. Very much less

2245. Boiling point diagram is not affected by the ambient______________________?
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A. Pressure

B. Humidity

C. Temperature

D. Both B. and C.
2246. The dew point of a saturated gas phase equals the ________________ temperature?
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A. Gas

B. Room

C. Wet bulb

D. None of these

2247. A cottrell precipitator makes use of the ______________ for dusty air cleaning?
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A. Alternating current

B. Corona discharge

C. None of these

D. Electric spark

2248. Crushing efficiency is the ratio of the ______________________ ?
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A. Energy absorbed by the solid to the surface energy created by crushing

B. Energy absorbed by the solid to that fed to the machine

C. Surface energy created by crushing to the energy absorbed by the solid

D. Energy fed to the machine to the surface energy created by crushing

2249. ______________ are used for the separation of coarse particles from a slurry of fine particles?
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A. Classifiers

B. Hydrocyclones

C. Decanters

D. Thickeners

2250. Paddle agitator_________________?
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A. Produces axial flow

B. None of these

C. Is suitable for mixing low viscosity liquids

D. Moves at very high speed