mtn4 Flashcards
Which of the following can be calculated theoretically using
steam table and Dalton’s law of partial pressure; if the relative
humidity and dry bulb temperature of moist air is known?
A. Dew point
B. Humidity ratio
C. Wet bulb temperature
D. None of these
C
Which of the following is the correct ternary diagram for liquid
liquid extraction system comprising of two pairs partly soluble
(e.g., chlorobenzene-water-methyl ethyl ketone system)?
A
Steam distillation is used for separation of high boiling
A. substances from non-volatile impurities.
B. volatile impurity from still higher boiling substances.
C. both (a) and (b).
D. neither (a) nor (b).
C
The slope of 9-line is determined by the
A. reflux ratio
B. plate efficiency to be achieved
C. thermal condition of the feed
D. relative volatility.
C
The feed to fractionating column is changed from saturated
vapour to saturated liquid. If the separation and reflux ratio
remains unchanged, the number of ideal stages will
A. increase
B. decrease
C. remains same
D. depend on saturated boiling point; may increase or
decrease
A
Rose oil is extracted from rose leaves using _______ distillation.
A. high pressure
B. low pressure
C. extractive
D. steam
D
Rose = steam
Hypersorption refers to a __________ process.
A. fixed bed absorption
B. moving bed absorption
C. fixed bed adsorption
D. moving bed adsorption
D
Extraction of coffee from its seed is done by
A. liquid-liquid extraction.
B. leaching.
C. extractive distillation.
D. steam distillation.
B
In azeotropic mixture, the equilibrium vapour composition is
A. more than liquid composition.
B. less than liquid composition.
C. same as liquid composition.
D. independent of pressure.
C
(Eq = same)
With lapse of time, the overhead composition of light component
in case of batch distillation with constant reflux
A. increases
B. decreases
C. remains same
D. may increase or decrease ; depends on system.
B
lapse = decrease
According to the film theory of mass transfer, the mass transfer
co-efficient is proportional to (where, D = molecular diffusivity)
A. D
B. D2
C. D0.5
D. 1/D
A
Dry bulb temperature of the gas is _____ the wet bulb temp.
A. less than
B. more than
C. equal to
D. none of these
B
Decoction refers to the use of solvent
A. at ambient temperature
B. at its boiling point
C. in its vapor form
D. none of these
B
Flooding in a column results due to
A. high pressure drop
B. low pressure drop
C. low velocity of the liquid
D. high temperature
A
Flash distillation is suitable for separating the constituents of a
binary system, which
A. form minimum boiling azeotrope.
B. have very wide boiling points.
C. have very close boiling points.
D. form constant boiling azeotrope.
B
Lewis number, which is important in problems involving
simultaneous heat and mass transfer, is the ratio of
A. mass diffusivity to momentum diffusivity.
B. thermal diffusivity to mass diffusivity.
C. momentum diffusivity to thermal diffusivity.
D. none of these.
B
The ratio of Murphree plate efficiency to point efficiency is 1 in a
__________ flow model.
A. Plug
B. perfectly mixed
C. both (a) & (b)
D. neither (a) nor (b)
B
The rough value of diffusion co-efficient of water vapor into air
at 25°C may be about __________ cm2/sec.
A. 0.25
B. 2.5
C. 1.25
D. 0.0025
A
Which of the following gas-liquid contacting devices incurs the
least pressure drop for a particular duty ?
A. Grid tray tower
B. Perforated tray tower
C. Wetted wall tower
D. Bubble cap tower
C
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?
A. The mixture exhibits an azeotrope at 101.3 kPa.
B. The composition of the mixture, in percent by volume
is: o-xylene 30, p-xylene 60. and m-xylene 10.
C. The composition of the mixture in mole percent is: o
xylene 30, p-xylene 60 and m-xyoene 10.
D. The mixture contain optical isomers.
A
Unsaturated air (with dry bulb temperature and dew point being
35°C and 18°C respectively) is passed through a water spray
chamber maintained at 15°C. The air will be cooled
A. and humidified.
B. and dehumidified with increase in wet bulb
temperature.
C. at the same relative humidity.
D. and dehumidified with decrease in wet bulb
temperature.
D
Unit operation involved in the prilling of urea is
A. evaporation
B. drying
C. crystallization
D. both (b) and (c)
D
Pick out the wrong statement pertaining to leaching.
A. Fine solids can not be leached in a Pachuka tank.
B. Door classifier can be used for leaching of coarse
solids.
C. Vegetable seeds can be leached in either of Bollman
extractor, Rotocel or Kennedy extractor.
D. Very high temperature is not needed for the leaching of
sugar beet.
A
Molecular seives are porous
A. alumina.
B. silica.
C. synthetic zeolites crystals/metal alumino-silicates.
D. none of these.
C
The process employing desorption of the absorbed solute by a
solvent is called
A. elution
B. osmosis
C. reverse osmosis
D. sublimation
A
If the overall efficiency and Murphree plate efficiency are equal,
then both the equilibrium and operating lines are
A. straight
B. parallel
C. both (a) & (b)
D. neither (a) nor (b)
C
Which of the following operations does not involve leaching ?
A. Dissolving gold from ores.
B. Dissolving pharmaceutical products from bark or roots.
C. Dissolving sugar from the cells of the beet.
D. Removing nicotine from its water solution by kerosene.
D
The recovery of pencillin from the acidified fermentation broth is
done by
A. Distillation
B. Evaporation
C. Absorption
D. liquid extraction
D
Calcium ammonium nitrate (a fertiliser) is dried in a _____ dryer.
A. Rotary
B. Vacuum
C. Tunnel
D. Tray
A
A binary mixture of benzene and cyclohexane is separated by
A. flash vaporization
B. extractive distillation
C. solvent extraction
D. ordinary distillation
B
Component A is diffusing in a medium B. The flux NA relative to
a stationary point is = to the flux due to molecular diffusion, if
A. mass transfer is accompanied by reaction.
B. diffusion of A is in stagnant medium B.
C. molecular mean free path is high.
D. there is equimolar counter diffusion.
D
Stationary = equi
Cox chart is useful in the design of
A. distillation column
B. evaporator
C. dryer
D. crystallizer
A
Absorption factor, for a fixed degree of absorption from a fixed
amount of gas should be
A. 1
B. > 1
C. < 1
D. ≤ 1
B
Selectivity of the solvent used in solvent extraction should be
A. 1
B. > 1
C. < 1
D. 0
B
Dew point of an air-water vapor mixture
A. decreases with decrease in pressure.
B. at constant humidity & total pressure is fixed.
C. corresponding to any point on the humidity chart is
obtained by projecting a line through this point parallel
to the temperature axis and to the saturation curve.
D. all ‘a’, ‘b’ & ‘c’.
D
Can a cooling tower cool water below the wet bulb temperature
of inlet air?
A. yes
B. no
C. yes; but height of cooling tower will be prohibitively
high.
D. yes; but the air flow rate should be excessively high
B
The solvent used in liquid-liquid extraction should have
__________ less than one.
A. Selectivity
B. distribution co-efficient
C. both (a) and (b)
D. neither (a) nor (b).
D
(Less than = neither)
The suitable evaporator for concentration of foaming liquids is a
__________ evaporator.
A. long tube
B. short tube
C. vacuum
D. falling film
A
The ratio of Murphree plate efficiency to point efficiency is
always > 1 in a __________ flow model.
A. Plug
B. perfectly mixed
C. both (a) & (b)
D. neither (a) nor (b)
A
Tea percolation employs
A. liquid-liquid extraction
B. leaching
C. absorption
D. none of these
B
NSc/NPr is called the
A. psychrometric ratio
B. Lewis number
C. Sherwood number
D. Stantan number
B
McCabe-Thiele method
A. uses molal units for material and energy balance.
B. uses weight fractions to express liquid and vapour
composition.
C. can use any type of units.
D. is more accurate than Ponchan-Savarit method.
A
The film penetration model of mass transfer was enunciated by
A. Gilliland
B. Toor and Marchello
C. Stefan
D. Fick
B
film = toor
The most economical range of absorption factor is
A. 0 to 0.5
B. 0 to 3
C. 1.25 to 2
D. 5 to 15
C
Channelling is most severe
A. in towers packed with stacked packing.
B. in towers packed randomly with crushed solids.
C. in dumped packing of regular units.
D. at very high liquid flow rate.
A
Out of two equilibrium curves, first one lies above the diagonal
and the second lies below the diagonal in the x-y plot. It means
that separation by distillation is
A. not possible in the second case unless vacuum is
applied.
B. not possible in the second case unless high pressure
is applied.
C. more readily done in the second case compared to first
one.
D. none of these
C
out of two = more
ADDUCTS’ and ‘CLATHRATES’ are used in case of
A. extractive distillation.
B. crystallisation.
C. absorption.
D. none of these.
B
Adsorption is an unit operation which generally involves
__________ systems.
A. liquid-solid
B. gas-solid
C. fluid-solid
D. solid-solid
C
In case of __________ distillation, a solvent is added to alter the
relative volatility of the mixture to be separated.
A. Molecular
B. Azeotropic
C. Extractive
D. flash.
C
Separation of the isotopes of helium for scientific investigations
is done by
A. reverse osmosis
B. thermal diffusion
C. leaching
D. solvent extraction
B
In a binary system, separation is very efficient, when the relative
volatility is
A. 1
B. > 1
C. < 1
D. 0.5
B
Fenske-Underwood equation used for calculating the minimum
number of theoretical plates in distillation column is valid for
A. constant molal overflow
B. total reflux
C. constant relative volatility
D. all (a), (b) and (c)
D
The binary diffusivity in gases does not depend upon the
A. pressure
B. temperature
C. nature of the components
D. none of these
C
Berl saddle made of carbon cannot be used for
A. alkalis
B. SO2
C. H2SO4
D. oxidising atmosphere
D
1 kg of a saturated aqueous solution of a highly soluble
component A at 60°C is cooled to 25°C. The solubility limits of
A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C.
The amount in kg of the crystals formed is
A. 0.4
B. 0.25
C. 0.2
D. 0.175
C
During drying of a solid, the critical moisture content increases
with
A. decreased drying rate
B. increased thickness of the solid
C. increased drying rate
D. both (b) and (c).
D
Priming in a distillation column
A. results from very low gas velocity.
B. is desirable from point efficiency consideration.
C. is characterised by the presence of foam throughout
the space between trays.
D. reduces the overall pressure drop.
C
priming = foam
The commonly used solvent in supercritical extraction is
A. methyl ethyl ketone.
B. water.
C. carbon tetrachloride.
D. carbon dioxide.
D
(Supercritical = CO2
When the liquid over a plate is of uniform concentration, then
A. Murphree efficiency > point efficiency.
B. Murphree efficiency < point efficiency.
C. Murphree efficiency = point efficiency.
D. Murphree efficiency ≠ point efficiency.
C
In saturated gas, the
A. vapour is in equilibrium with the liquid at the gas
temperature.
B. vapour is in equilibrium with the liquid at the room
temperature.
C. partial pressure of vapour equals the vapour pressure
of the liquid at room temperature.
D. none of these
A
As per Gilliland’s equation, the diffusivity is
A. directly proportional to ‘T1.5’.
B. inversely proportional to ‘P’.
C. dependent on the molecular volume & molecular
weight of components.
D. all ‘a’, ‘b’ & ‘c’.
D
What is the degree of freedom of an absorption process in which
only one component is transferred between phases?
A. 3
B. 2
C. 4
D. 1
A
Pick out the wrong statement.
A. When the concentration difference for the mass
transfer becomes zero at the bottom of the gas
absorption tower, then the upper end of the operating
line touches the equilibrium curve.
B. The average distance between the operating line and
equilibrium line is large, when the liquid-gas ratio is
also large in case of a counter current gas absorption
tower.
C. The operating line lies above the equilibrium curve in
case of a gas desorber.
D. With decrease in the liquid flow rate for a fixed gas flow
rate, the slope of the operating line decreases, in case
of gas absorption process.
C
A mixture of 10% C6H6 vapour in air at 25°C and 750 mm Hg
has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg
will be around __________ °C.
A. 21.7
B. 20
C. 27.3
D. 18.7
D
Which of the following is not fixed by the process requirements,
in the design of absorbers ?
A. Flow rate of the entering gas.
B. Composition of the entering liquid.
C. Terminal concentrations of gas stream.
D. None of these.
D
If the amount of the steam used in steam distillation is increased,
the temperature of distillation
A. Increases
B. Decreases
C. remains unchanged
D. depends on relative volatility
B
^ Steam, v temp
Moisture in a solid exerting an equilibrium vapour pressure equal
to that of the pure liquid at the same temperature is called the
__________ moisture.
A. Unbound
B. Critical
C. Free
D. Bound
A
Inside the distillation columns, the
A. highest temperatures is near the feed plate.
B. driving force for the liquid flow is its weight.
C. vapors are not always at their dew points.
D. all (a), (b) and (c)
B
When the psychometric ratio is __________ then the adiabatic
saturation temperature and wet bulb temperature becomes
equal.
A. 1
B. < 1
C. > 1
D. ∞
A
Becomes equal = 1
Desirable value of absorption factor in an absorber is
A. 1
B. < 1
C. > 1
D. 0.5
C
Refractory bricks are usually dried in a __________ dryer.
A. Tray
B. Tunnel
C. Conveyor
D. Festoon
B
For __________ drying, the effects of velocity, temperature and
humidity of the gas and the thickness of the solid are the same.
A. unsaturated surface
B. constant rate
C. both (a) and (b)
D. neither (a) nor (b).
C
What is the degree of freedom of an absorption process in which
only one component is transferred between phases?
E. 3
F. 2
G. 4
H. 1
A
Sticky material can be dried in a __________ dryer.
A. Tray
B. Rotary
C. fluidised bed
D. none of these
A
Langmuir equation is associated with
A. leaching
B. adsorption
C. steam distillation
D. multicomponent absorption.
B
During the constant rate period of drying of a solid,
A. increased air humidity decreases the rate of drying.
B. increasing the air temperature decreases the drying
rate.
C. surface evaporation of unbound moisture occurs.
D. none of these.
C
At a fixed total pressure, humidity depends only on the
A. partial pressure of vapour in the mixture.
B. heat capacity of the vapour.
C. density of the vapour.
D. none of these.
A
If moisture content of solid on dry basis is X, then the same on
wet basis is
A. XX+1
B. X1-X
C. 1+XX
D. 1-XX
A
Flash distillation is
A. same as differential distillation.
B. used for multicomponent systems like crude refining.
C. same as simple distillation.
D. most useful for handling binary systems.
B
_________ developed the film theory.
A. Higbie
B. Fick
C. Ergun
D. Levenspeil
A
For absorbers, high pressure drop results in
A. increased efficiency.
B. decreased efficiency.
C. high operating cost.
D. better gas liquid contact.
C
Which of the following parameters remains almost constant
during adiabatic saturation of unsaturated air?
A. Dry bulb temperature
B. Dew point
C. Wet bulb temperature
D. None of these
C
Remains almost constant = wet bulb
Coffee is prepared from coffee beans by leaching with
A. cold water
B. hot water
C. dilute hot caustic solution
D. naphtha
B
Gaseous diffusion co-efficient increases with increase in the
A. pressure
B. temperature
C. both (a) & (b)
D. neither (a) nor (b)
B
With increase in absolute humidity, the dew point of an
unsaturated mixture of air and water vapor (at constant pressure
and temperature)
A. increases
B. remains unchanged
C. decreases
D. decreases linearly
A
Inc in abs humid = inc in dew pt
If xD = overhead product molal composition and RD = reflux ratio,
then slope and intercept of the operating line for rectifying
section are respectively
A. XD/RD+1 , RD/RD+1
B. RD/RD+1 , XD/XD+1
C. XD/RD+1 , RD+1/RD
D. ,
B
Pick out the wrong statement. Raoult’s law does not apply, when
the
A. size of component molecules are not equal.
B. attractive forces between like and unlike molecules in
the solution are approximately equal.
C. component molecules are nonpolar.
D. chemical combination or molecular association
between unlike molecules takes place in the formation
of solution.
C
Water-ethyl alcohal solution can be concentrated (in respect of
alcohal concentration) by __________ distillation.
A. Atmospheric
B. Vacuum
C. high pressure
D. none of these
B
L/mG is the expression for
A. absorption factor
B. Brinkman number
C. slope of operating line in absorber
D. slope of operating line in stripper.
A
Extraction of pencillin employs a ________ extraction coloumn.
A. Centrifugal
B. Packed
C. Plate
D. None of these.
A
In case of gases, the binary diffusivity is proportional to (where,
P = pressure)
A. P
B. 1/P
C. 1/√P
D. √P
B
When the gas to be dissolved in liquid is a/an __________ then
normally co-current adsorber are used.
A. mixture of two gases
B. pure gas
C. ideal gas
D. sparingly soluble gas
B
(Co-current = pure)
Corresponding to Prandtl number in heat transfer, the
dimensionless group in mass transfer is the __________
number.
A. Schmidt
B. Sherwood
C. Peclet
D. Stanton
A
If a two phase system is in physical equilibrium; then it means
that, the
A. escaping tendency of each component from the liquid
phase to the vapor phase is exactly equal to that from
vapor phase to liquid phase.
B. temperature of the liquid phase is equal to that of the
vapor phase.
C. total pressure throughout the liquid phase is equal to
that throughout the vapor phase.
D. all (a), (b) and (c).
D
McCabe-Thiele method of binary distillation does not assume
that the
A. sensible heat changes are negligible compared with
latent heat changes.
B. molar latent heats of all components are equal.
C. heat of mixing is negligible.
D. none of these
D
(NSh/NRe∙NSc) is termed in mass transfer operation as the
A. Stanton number
B. Peclet number
C. thermal diffusivity
D. momentum diffusivity
A
The Hatta number is important in
A. multicomponent distillation.
B. binary distillation.
C. gas absorption without chemical reaction.
D. gas absorption with chemical reaction.
D
When a multistage tray tower uses a min. reflux ratio, it implies
A. infinite trays and maximum reboiler heat load.
B. infinite trays and minimum reboiler heat load.
C. minimum trays and minimum reboiler heat load.
D. minimum trays and maximum reboiler heat load.
B
CO2 can be absorbed by
A. hot cupric oxide
B. heated charcoal
C. cold Ca(OH)2
D. alumina
B
For the same process conditions, the reflux ratio of an unlagged
distillation column
A. decreases in winter
B. increases in winter
C. increases in summer
D. none of these
B
An ideal tower packing should not
A. have low weight per unit volume.
B. have large surface area per unit volume.
C. have large free cross-section.
D. hold up large amount of liquid in the packing.
D
Which of the following is a suitable absorbent for removal of H2S
from natural gas?
A. Vetrocoke solution
B. Monoethanol amine (MEA)
C. Dilute
D. Hot water
B
Acetone is to be removed from air in an isothermal dilute
absorber using pure water as solvent. The incoming air contains
5 mole% of acetone (yin = 0.05). The design equation to be used
for obtaining the number of trays (N) of the absorber is, N+2 = 6
log (yin/yout).For 98% recovery of acetone, the number of trays
required is/are
A. 1
B. 8
C. 9
D. 10
C
Schimdt number and Lewis number for pure air at atmospheric
conditions are respectively
A. < 1 and ≈ 1
B. 1 and 0
C. >1 and ≈ 1
D. 0 and ≈ 1
A
Below is given an equilibrium moisture curve of a substance.
State which regions represent free moisture and unbound
moisture respectively.
A. II, III
B. II, IV
C. IV, III
D. IV, II
A
Molecular diffusion is caused by the
A. transfer of molecules from low concentration to high
concentration region.
B. thermal energy of the molecules.
C. activation energy of the molecules.
D. potential energy of the molecules.
B
At __________ reflux, theoretical number of plates in a
distillation coloumn is calculated using Fenske-Underwood
equation.
A. Operating
B. Total
C. Minimum
D. maximum permissible
B
Separation of a mixture of two gases by absorption in the liquid
solvent depends upon the difference in their
A. viscosity
B. density
C. solubility
D. relative volatility
C
Components, having widely different boiling point in a binary
mixture, can be separated using __________ distillation.
A. Molecular
B. Extractive
C. Steam
D. Simple
D
Which of the following equipments is not used in liquid-liquid
extraction ?
A. Pachuka tank
B. Agitated vessels
C. Centrifugal extractors
D. Packed towers
A
Pick out the wrong statement.
A. Packed towers are preferred for vacuum operation,
because the pressure drop through the packing is less
and they (packings) also lessen the possibility of tower
wall collapse.
B. Packed towers are preferred over plate towers for
handling corrosive and foamy liquids.
C. Diameter of randomly packed tower is normally more
than 1.2 metres.
D. Due to uneven supply and improper distribution of
liquid, problem of channeling, loading & flooding is
generally encountered in packed towers.
C
Equilibrium-moisture curves of different solids
A. are different
B. are same
C. depend on the humidity of the gas
D. none of these
A
Azeotropism for ethyl alcohol-water system disappears by
A. increasing temperature
B. decreasing pressure
C. increasing pressure
D. no means
B
Degree of freedom for leaching & solvent extraction process is
A. 1
B. 3
C. 0
D. 2
B
Diffusion co-efficient generally depends upon the temperature,
pressure & the nature of the components of the system. Its
dimension is not the same as that of the
A. mass transfer co-efficient.
B. thermal diffusivity.
C. kinematic viscosity.
D. volumetric diffusivity.
A
In the absorption of ammonia in water, the main resistance to
absorption is by the __________ phase.
A. Liquid
B. Gas
C. both (a) & (b)
D. neither (a) nor (b)
B
Drying of refractory is normally carried out in a ________ dryer.
A. open pan
B. tray
C. rotary vacuum
D. truck/tunnel.
D
The expression, ln(F/W) = xWxFdxy*-x is
A. differential distillation equation
B. for NtoG in absorption for dilute mixture
C. slope of q-line in McCabe-Thiele method
D. for relative volatility
A
Heat sensitive materials with very high latent heat of
vaporisation may be economically separated using
A. liquid extraction
B. distillation
C. evaporation
D. absorption
A
Drift in a cooling tower is
A. the water entrained by the circulating air.
B. dependent on the water lost by evaporation.
C. desirable.
D. all (a), (b) & (c).
A
When the solvent dissolves very little of solute, then
A. solvent of low latent heat of vaporisation should be
used.
B. solvent of low freezing point should be used.
C. large quantity of solvent is required to extract the
solute.
D. very small quantity of solvent is required.
C
Equilibrium moisture of a solid is equal to the total moisture
minus free moisture. Which of the following substances will have
maxi-mum equilibrium moisture ?
A. Anthracite coal
B. Rag paper
C. Bamboo
D. Inorganic solids
C
An alkaline solution is used to reduce the concentration of
carbon dioxide in a stream from 10% to 0.1% by absorption with
irreversible chemical reaction. The overall number of transfer
units based on gas phase is
A. 9.21
B. 4.605
C. 100
D. 0.001
B
HETP is numerically equal to HTU, only when the operating line
A. lies below the equilibrium line.
B. lies above the equilibrium line.
C. and equilibrium lines are parallel.
D. is far from the equilibrium line.
C
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.
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 condensor and reboiler loads are higher in case
(ii) as compared to case (i).
D
Steady state equimolal counter diffusion occurs in case of
A. Leaching
B. Absorption
C. binary phase distillation
D. liquid-liquid extraction
C
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
A. Nsh = 2
B. Nst = 2
C. Nsc = 2
D. none of these
A
An air-water vapour mixture has a dry bulb temperature of 60°C
and a dew point temperature of 40°C. The total pressure is 101.3
kPa and the vapour pressure of water at 40°C and 60°C are 7.30
kPa and 19.91 kPa respectively.The humidity of air sample
expressed as kg of water vapour/kg of dry air is
A. 0.048
B. 0.079
C. 0.122
D. 0.152
D
The relative saturation of an unsaturated mixture of gas and
vapor is independent of the
A. nature of the vapor.
B. temperature of the mixture.
C. composition of the mixture.
D. none of these.
D
The adiabatic saturation curve for a vapour-gas mixture is
A. straight line.
B. slightly concave upward.
C. slightly concave downward.
D. none of these.
B
Pick out the wrong statement.
A. Cellulose acetate membranes are used in dialysis
process.
B. Elutriation process refers to when the soluble material
is largely concentrated on the surface of an insoluble
solid and is simply washed off by the solvent.
C. ‘Cascade’ means a group of stages interconnected so
that various streams flow from one to another.
D. Zirconia probe is used for the humidity measurement.
D
The value of NA/(NA + NB), for steady state equimolal counter
diffusion of two gases ‘A’ and ‘B’ is
A. 1
B. ∞
C. 0.5
D. 2
B
Equimolar counter = infinity
With increase in the concentration of the adsorbate, the integral
heat of adsorption
A. increases.
B. decreases.
C. remains unchanged.
D. may increase or decrease; depends on the type of
adsorbate.
B
Adsorbate = opposite
Small dia distillation column can be a
A. packed column
B. sieve tray
C. bubble cap
D. any of these
A
If mass diffusivity in a mixture is equal to the thermal diffusivity,
then the Lewis number is
A. 0
B. 1
C. < 1
D. > 1
B
_________ column is used in gas absorption process.
A. Wetted wall
B. Seive/perforated tray
C. Bubble cap
D. Packed
D
Nitrobenzene (boiling point = 210.6°C) is steam distilled at 1 atm
pressure.Nitrobenzene will distill off __________ °C.
A. at < 100
B. at > 210.6
C. between 100 and 210
D. none of these
A
Unit of molal diffusivity is
A. cm2/sec gm . mole
B. gm moles/cm2 . sec
C. gm moles/cm. sec
D. gm moles/cm2. Sec
C
Pick out the wrong statement.
A. With decrease in feed temperature, the number of
plates required for binary distillation decreases for a
given L/V ratio.
B. The extraction per unit of total height for a short packed
column is more effective than for a tall column, in case
of liquid-liquid extraction.
C. Natural draft cooling towers are made of ferro-concrete
and its cross-section is wider at the bottom.
D. Vanderwall adsorption is also called chemisorption.
D
At what value of reflux ratio, number of theoretical plates in a
distillation column is minimum ?
A. 0
B. 1
C. ∞
D. < 1
C
Batch tray dryers suffers from the disadvantage of
A. high maintenance cost.
B. non-uniform & low production rate.
C. high labour cost & low heat economy.
D. all ‘a’, ‘b’ & ‘c’.
C
__________ column is preferred to be used, when a high liquid
hold up is required in a reactor for gas-liquid reaction.
A. Packed
B. Bubble
C. Spray
D. Tray
B
High liquid hold up = bubble
The ‘shanks system’ of leaching (i.e., counter-current multiple
contact leaching) is used for
A. recovery of tannis from the tree barks and woods.
B. leaching sodium nitrate from Chilean nitrate bearing
rock.
C. both (a) and (b).
D. neither (a) nor (b).
C
Penetration model (theory) for mass transfer was enunciated by
A. Danckwerts
B. Toor and Marchello
C. Higbie
D. Kissinevskii
C
Surface renewal model of mass transfer was enunciated by
A. Toor and Marchello
B. Fick
C. Danckwerts
D. Stefan
C
For turbulent mass transfer in pipes, the Sherwood number
depends on the Reynolds number as
A. Re0.33
B. Re0.53
C. Re0.83
D. Re
C
Reverse osmosis is also called
A. dialysis
B. electrodilysis
C. diffusion
D. ultrafiltration.
D
Which of the following is not a batch drier?
A. Truck drier
B. Agitated pan drier
C. Fluidised bed drier
D. Vacuum shelf drier
C
The relative humidity of air decreases in-spite of an increase in
the absolute humidity, when the
A. temperature rises.
B. pressure rises.
C. temperature falls.
D. pressure falls.
A
warmer air can hold more water vapor, reducing the relative humidity percentage
The term “approach” in a cooling tower refers to the difference
in the temperature of the
A. cold water leaving the tower and the wet bulb
temperature of the surrounding air.
B. hot water entering the tower and the wet bulb
temperature of the surrounding air.
C. hot water entering and the cooled water leaving the
cooling tower.
D. none of these
A
In a moderately sized packed absorption tower, channeling
(which is most severe with stacked packings) can be minimised
by taking the ratio of tower diameter to packing diameter
A. > 4 :1
B. < 8 : 1
C. > 8:1
D. < 6:1
C
When the __________ the relative humidity of air decreases,
despite an increase in the absolute humidity.
A. temperature rises
B. pressure rises
C. temperature falls
D. pressure falls
A
Binary distillation involves the mass transfer by __________ at
the gas-liquid interface.
A. unidirectional diffusion from liquid to gas phase
B. unidirectional diffusion from gas to liquid phase
C. either ‘a’ or ‘b’
D. a counter diffusion at an almost equal molar rate
D
In a gas-liquid absorption coloumn, for obtaining the maximum
absorption efficiency
A. liquid stream should be distributed uniformly.
B. gas stream should be distributed uniformly.
C. both gas as well as liquid streams should be distributed
uniformly.
D. by passing should be completely avoided.
C
Steam distillation is not recommended to be used, if the
A. azeotropic mixture is to be separated and the final
product is miscible with water.
B. liquids decompose, if distilled directly at atmospheric
pressure.
C. material can not be distilled by indirect heating even
under low pressure, because of the high boiling
temperature.
D. material to be distilled is thermally unstable or has the
tendency to react with other components associated
with it, at the boiling temperature.
A
Rayleigh equation applies to __________ distillation.
A. Differential
B. Flash
C. Equilibrium
D. Molecular
A
Danckwerts developed the __________ theory.
A. Penetration
B. surface renewal
C. film
D. none of these
B
Mass transfer co-efficient ‘K’ according to penetration theory
varies with mass diffusivity as
A. D^0.5
B. D
C. 1/D
D. D^1.5
A
Most important factor to be considered in the selection of
packings for absorbers is the __________ of packing.
A. Size
B. Durability
C. Porosity
D. Cost
C
_________ is the separation technique used for desalination of
sea water.
A. Thermal diffusion
B. Reverse osmosis
C. Adsorption
D. Absorption
B
The relative saturation of a partially saturated mixture of vapour
and gas can be increased by __________ of the mixture.
A. reducing the total pressure
B. increasing the total pressure
C. reducing the temperature
D. both (b) and (c)
D
Molecular distillation is
A. high temperature distillation
B. for heat-sensitive materials
C. very low pressure distillation
D. both (b) and (c)
D
Drying of a wet solid under constant drying conditions means the
exposure of the wet solid to the air of constant
A. humidity
B. velocity
C. temperature
D. all (a), (b) & (c)
D
Which of the following provides maximum contact surface for a
liquid-vapour system?
A. Packed tower
B. Bubble-cap plate column
C. Seive-plate column
D. Wetted wall column
A
Which of the following is the correct ternery diagram for liquid
liquid extraction system comprising of one pair partly soluble
(e.g. water-benzene-acetic acid in which A-diluent, B - solvent
and C - solute)?
A
For experimental determination of mass transfer co-efficient by
wetted wall tower, the mass transfer area is
A. Calculated
B. Unknown
C. Known
D. not required
C
In stripping section of continuous distillation column, the
A. liquid is stripped of high boiler.
B. liquid is enriched with high boiler.
C. vapour is stripped of low boiler.
D. none of these.
B
Molality is defined as the number of gm moles of solute per
__________ of solvent.
A. Litre
B. Gm
C. Kg
D. m3
C
________ is concerned with the adsorption equilibria.
A. Fick’s law
B. Gibb’s equation
C. Freundlich equation
D. none of these
C
Fractional solvent extraction
A. employs only one solvent
B. employs two solvents
C. results in low interfacial tension
D. none of these
B
Fractional = 2
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
A. at ground level.
B. 2 metres above the ground.
C. 5 metres above ground.
D. 10 metres above ground.
A
Raschig ring made of procelain cannot be used for treating
concentrated
A. hydrochloric acid
B. nitric acid
C. alkalis
D. sulphuric acid
C
H2S present in naphtha reformed gas is removed by absorbing
with
A. ethanolamine
B. K2CO3
C. HCl
D. vacuum gas oil
A
During constant rate drying period, vaporisation rate per unit
drying surface area
A. decreases with time.
B. increases with time.
C. does not change with time,
D. does not affect the moisture content of the wet solid.
C
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
A. increases
B. decreases
C. remains unaffected
D. passes through a maximum
A
Pick out the wrong statement.
A. Mass transfer co-efficient does not account for gase
liquid diffusion.
B. Diffusion co-efficient and mass transfer co-efficient are
not same in any mass transfer operation.
C. Contacting cold vapor-gas mixture with hot liquid
exemplifies humidification process.
D. Contacting cold liquid with warm vapor-gas mixture
exemplifies dehumidification process.
A
In rectifying section of a continuous distillation column, the
A. vapour is enriched with low boilers.
B. vapour is enriched with high boilers.
C. liquid is stripped of high boilers.
D. none of these.
B
According to Chilton-Colburn analogy for mass transfer,
NSt.NSc2/3 is equal to
A. f
B. f/2
C. 2f
D. 1/f
B
A pure drug is administered as a sphere and as a cube. The
amount of drug is the same in the two tablets. Assuming that the
shape and size do not influence the mass transfer, the ratio of
rate of dissolution in water at t = 0 for the cubic to spherical tablet
is
A. 0.54
B. 1.04
C. 1.24
D. 1.94
C
Minimum reflux ratio in a distillation column results in
A. optimum number of trays.
B. minimum reboiler size.
C. maximum condenser size.
D. minimum number of trays.
C
Flooding in a distillation column is detected by a sharp
A. increase in Murphree plate efficiency.
B. decrease in pressure drop.
C. decrease in liquid hold up in the coloumn.
D. increase in pressure drop.
D
