Mass Transfer Flashcards by Kris Daclan

Mass transfer rate between two fluid phases does not necessarily depend on the __________ of the two phases.

chemical properties
physical properties
degree of turbulence
interfacial area

chemical properties

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In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is

0.50
0.60
2
1

0.50

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Fenske equation determines the
maximum number of ideal plates.
height of the distillation column.
minimum number of theoretical plates.
optimum reflux ratio.

minimum number of theoretical plates.

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The term “cooling range” in a cooling tower refers to the difference in the temperature of

cold water leaving the tower and the wet bulb temperature of the surrounding air.
hot water entering the tower and the wet bulb temperature of the surrounding air.
hot water entering the tower and the cooled water leaving the tower.
none of these

hot water entering the tower and the cooled water leaving the tower.

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Which of the following is the most suitable for extraction in a system having very low density difference ?

Mixer-settler extractor
Centrifugal extractor
Pulsed extractor
Packed extraction tower

Centrifugal extractor

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Total reflux in a distillation operation requires minimum
reboiler load
number of plates
condenser load
all (a), (b) and (c)

number of plates

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The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by
raising the temperature.
lowering the total pressure.
both (a) and (b).
neither (a) nor (b).

both (a) and (b).

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The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is
+ve
-ve
zero
none of these

+ve

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Fenske’s equation for determining the minimum number of theoretical stages in distillation column holds good, when the
relative volatility is reasonably constant.
mixture (to be separated) shows negative deviation from ideality.
mixture (to be separated) shows positive deviation from ideality.
multicomponent distillation is involved.

relative volatility is reasonably constant.

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When the temperature and humidity of air is low, we usually use __________ draft cooling tower.
natural
forced
induced
none of these

natural

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Pick out the correct statement.
In case of liquid-liquid extraction, no separation is possible, if the selectivity of the solvent used is unity.
With increase in temperature, the selectivity of the solvent used in solvent extraction decreases.
The selectivity of solvent used in solvent extraction is unity at the plait point.
all (a), (b) and (c).

all (a), (b) and (c).

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__________ columns are used for liquid dispersion in a continuous gas phase.
Packed
Pulse
Bubble cap
Sieve plate

Packed

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Overall efficiency of the distillation column is
the ratio of number of ideal plates to actual plates.
the ratio of number of actual plates to ideal plates.
same as the Murphree efficiency.
always more than the point efficiency.

the ratio of number of ideal plates to actual plates.

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Which is the controlling factor for a drum drier?
Diffusion
Heat transfer
Both (a) and (b)
Neither (a) nor (b)

Heat transfer

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Drying operation under vacuum is carried out to
dry those materials which have very high unbound mositure content.
reduce drying temperature.
increase drying temperature.
dry materials having high bound moisture content.

reduce drying temperature.

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Air initially at 101. 3 kPa and 40°C and with a relative humidity of 50%, is cooled at constant pressure to 30°C. The cooled air has a
higher dew point.
higher absolute (specific) humidity.
higher relative humidity
higher wet bulb temperature.

higher relative humidity

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Separation of two or more components of a liquid solution can not be achieved by
fractional crystallisation
liquid extraction
absorption
evaporation

absorption

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Stefan’s law describes the mass transfer by
diffusion
bulk flow
both ‘a’ & ‘b’
neither ‘a’ nor ‘b’

both ‘a’ & ‘b’

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At minimum reflux ratio for a given separation
number of plates is zero.
number of plates is infinity.
minimum number of the theoretical plates is required.
separation is most efficient.

number of plates is infinity.

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Relative humidity is the ratio of the

partial pressure of the vapour to the vapour pressure of the liquid at room temperature.
partial pressure of the vapour to the vapour pressure of the liquid at gas temperature.
actual humidity to saturation humidity.
none of these

partial pressure of the vapour to the vapour pressure of the liquid at gas temperature.

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In batch distillation with constant reflux, overhead product composition __________ with time.
increases
decreases
does not vary
may increase on decrease, depends on the system.

decreases

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Psychrometry deals with the properties of gas-vapor mixture. Humidity can be determined by the measurement of the __________ of a fibre.
electrical resistance
thermal conductivity
strength
none of these.

electrical resistance

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Heat in BTU necessary to increase the temperature of 1 lb of gas and its accompanying vapour by 1°F is called the
latent heat
humid heat
specific heat
sensible heat

specific heat

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To increase the absorption factor, (where, G = gas flow rate, S = solvent flow rate)
increase both ‘G’ and ‘S’.
decrease both ‘G’ and ‘S’.
increase ‘S’ and decrease ‘G’.
increase ‘G’ and decrease ‘S’

increase ‘S’ and decrease ‘G’.

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The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________ 1 0.5 10 0

Dew point of a gas-vapour mixture increases with temperature rise. decreases with temperature rise. decreases with decrease in pressure. increases with increase in pressure.

decreases with decrease in pressure.

In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG __________ the absorption factor. increases with increase in is one at unity value of both (a) and (b) neither (a) nor (b)

both (a) and (b)

Which of the following plays an important role in problems of simultaneous heat and mass transfer ? Lewis number Schmidt number Prandtl number Sherwood number

Lewis number

In case of an absorber, the operating line always lies above the equilibrium curve. line always lies below the equilibrium curve. line can be either above or below the equilibrium curve. velocity is more than the loading velocity.

line always lies above the equilibrium curve.

As the reflux ratio in a distillation coloumn is increased from the minimum, the slope of the operating line in stripping section decreases. number of plates decreases very slowly first and then more and more rapidly. total cost first decreases and then increases. liquid flow increases while the vapor flow decreases for a system.

total cost first decreases and then increases.

Absorption factor is defined as (where, S1 = slope of the operating line S2 = slope of the equilibrium curve) S2/S1 S1/S2 S1 - S2 S1 x S2

S1/S2

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 ternery system containing twopairs of partially miscible liquids ? 0 1 2 3

Which of the following remains constant during sensible cooling process ? Specific humidity Partial pressure of vapour Both (a) and (b) Neither (a) nor (b)

Both (a) and (b)

Make up water is required in a cooling tower to replace the water lost by evaporation drift blowdown and leakage all (a), (b) and (c)

all (a), (b) and (c)

Which of the following quantities need not be fixed before starting the design of a co-current absorber ? Heat gain or loss Flow rate of entering liquid Flow rate of gas None of these

Flow rate of entering liquid

Mass transfer co-efficient of liquid is affected more by temperature than that for gases. affected much less by temperature than that for gases. not affected by the temperature. none of these.

affected more by temperature than that for gases.

Absorption accompanied with chemical reaction is exemplified by the absorption of ammonia in water. benzol present in coke oven gas by wash oil. SO2 in alkaline solution. all (a), (b) and (c).

SO2 in alkaline solution.

Which of the following unit operations makes use of Thiele-Geddes equation ? Liquid-liquid extraction Solid-liquid extraction Multicomponent absorption with chemical reaction Multicomponent distillation.

Multicomponent distillation.

Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty ? Sieve plate column Bubble cap column Randomly packed column Wetted wall column

Wetted wall column

The equipment frequently used for adiabatic humidification-cooling operation with recirculating liquid is natural draft cooling tower induced draft cooling tower spray chamber none of these

spray chamber

Chemisorption (chemical adsorption) is same as "Van der Waals" adsorption. characterised by adsorption of heat. an irreversible phenomenon. a reversible phenomenon.

an irreversible phenomenon.

The rate of solid-liquid extraction is limited by the phase change of the solute as it dissolves in the solvent. diffusion of the solute through the solvent in the pores to the outside of the particle. diffusion of the solute from the solution in contact with the particle to the main bulk of the solution. all 'a', 'b' & 'c'.

all 'a', 'b' & 'c'.

Raoult's law applies to the all liquid solutions non-ideal solution only. non-volatile solute. solvents.

solvents.

In distillation columns, the number of bubble caps per tray primarily depends upon the allowable liquid velocity. allowable gas velocity. allowable gas and liquid velocities. feed composition.

allowable gas and liquid velocities.

In distillation, overhead product contains only one component two components any number of components only saturated liquid

any number of components

With increase in pressure, the relative volatility for a binary system increases. decreases. remains same. either (a) or (b), depends on the system.

decreases

Low viscosity absorbent is preferred for reasons of rapid absorption rates and good heat transfer characteristics. improved flooding characteristics. low pressure drop on pumping. all (a), (b) and (c).

all (a), (b) and (c).

Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as K ∝ D K ∝ √D K ∝ D^1.5 K ∝ D^2

K ∝ D

The McCabe Δ L law states that the molar heats of vaporisation of components are nearly equal. linear crystal growth rate depends on the degree of supersaturation. linear crystal growth rate does not depend on the crystal size. linear crystal growth rate depends on the crystal size.

linear crystal growth rate does not depend on the crystal size.

Bollman extractor is a static bed leaching equipment. is used for extraction of oil from oilseed. is a centrifugal extractor. employs only counter-current extraction.

is used for extraction of oil from oilseed.

The relation, Sc = Pr = 1, is valid, when the mechanism of __________ ansfer is same. heat and mass mass and momentum heat and momentum heat, momentum and mass

heat and mass

A coalescer in a mixer-settler liquid-liquid extraction coloumn comprises of thin bed of substances of extended surface having high porosity. helps in increasing the bubble size entering the settler. helps in increasing the settling rate of the bubbles. all 'a', 'b', & 'c'.

all 'a', 'b', & 'c'.

For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will increase decrease remain same data insufficient, can't be predicted

increase

Pick out the correct statement. Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation. A sharp decrease in pressure drop is an indication of flooding in a distillation coloumn. Solvent used in extractive distillation should be of high volatility. Flash distillation is suitable for separating components which have very close boiling temperature.

Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation.

When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of vapour pressure of component A to that of component B. vapour pressure of component A to the total pressure. vapour pressure of component A to the partial pressure of A. partial pressure of component A to the total pressure.

vapour pressure of component A to that of component B.

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 decoction percolation elutriation or elution none of these

elutriation or elution

In the constant rate period of the rate of drying curve for batch drying, cracks develop on the surface of the solid. rate of drying decreases abruptly. surface evaporation of unbound moisture occurs. none of these.

surface evaporation of unbound moisture occurs.

It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%). 15 min 51 min 71 min 94 min

71 min

Agitator is provided in a crystalliser for avoiding deposition on cooler surfaces. formation of nuclei. crystal growth. all (a), (b) and (c).

all (a), (b) and (c).

__________ diffusion is used for separating the isotopes of methane. Thermal Pressure Concentration Force

Thermal

Ordinary diffusion process is also called __________ diffusion. pressure thermal concentration forced.

concentration

Pick out the wrong statement. Different solids have different equilibrium moisture curves. Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of theoretical plate calculation for distillation column. Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column. Even a forced draft cooling tower can not cool water below the wet bulb temperature.

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

Pick out the wrong statement pertaining to the rotary dryer. Flights (located in the inside shell of rotary dryer) lift the material being dried and shower it down through the current of hot air/gases. It extends from the wall to a distance which is about 8-12% of the inside diameter of shell. Hold up of a rotary drier is defined as the fraction of the dryer volume occupied by the solid at any instant. The best performance for rotary drier is obtained, when the hold up is in the range of 0.05 to 0.15. Rotary dryer is suitable for drying sticky material. Recommended peripherial speed of a rotary drier is in the range of 10 to 30 metres/minute.

Rotary dryer is suitable for drying sticky material.

The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives low pressure drop and high hold up. high pressure drop and low hold up. low pressure drop and low hold up. high pressure drop and high hold up.

low pressure drop and low hold up.

If the path of liquid across the plate is very long as in case of large diameter tower, Murphree efficiency can be __________ percent. 100 > 100 < 100 none of these

> 100

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 25% 50% 70% 90%

50%

Raoult's law is applicable to the ideal solutions real solutions mixture of water and alcohol non-ideal gases

ideal solutions

Weeping in a distillation column increases tray efficiency. provides large interfacial surface for mass transfer. results due to very high gas velocity. results due to very low gas velocity.

results due to very low gas velocity.

In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of area between operating line and 45° diagonal x-y diagram. condenser and reboiler surfaces. tower cross-section. none of these.

area between operating line and 45° diagonal x-y diagram.

Wetted wall tower experiment determines the molal diffusivity. volumetric co-efficient. mass transfer co-efficient. none of these.

mass transfer co-efficient.

In McCabe-Thiele method, at infinite reflux ratio the overhead product is minimum. both the operating lines coincide with diagonal. both (a) and (b). neither (a) nor (b).

the overhead product is minimum.

With decrease in the throughput (compared with the design capacity) for a bubble cap distillation column, its efficiency increases decreases remains same may increase or decrease ; depends on individual design

increases

Plate towers are preferred to packed towers, when large temperature changes are involved, because of the reason that the packing may be crushed due to thermal expansion/contraction of the components of the equipments. pressure drop in the equipment will be . very high. viscosity variation of the fluids may cause channeling/flooding. none of these.

packing may be crushed due to thermal expansion/contraction of the components of the equipments.

The equilibrium liquid composition compared to the vapor composition in case of azeotropic mixture is more less same either more or less; depends on the system

same

Out of the following gas-liquid contacting devices, for a given set of operating conditions, gas pressure drop is the least in __________ tower. wetted wall bubble cap perforated tray packed

wetted wall

Pick out the system with minimum boiling azeotrope at 1 atm. benzene-toluene ethyl alcohol-water hydrochloric acid-water all (a), (b) and (c)

ethyl alcohol-water

Free flowing granular materials can be best dried in a __________ drier. rotary cylinder drun freeze

rotary

In case of an ideal solution, the total vapor pressure varies __________ with the composition expressed as mole fraction, inversely linearly exponentially none of these

linearly

Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. Sherwood Schmidt Peclet Stanton

Sherwood

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 0.31 0.107 0.017 0.215

0.215

Liquid diffusivity is of the order of __________ cm2 /second. 0.01 0.1 10-5 to 10-6 > 1

10-5 to 10-6

The solvent used in liquid extraction should not have high latent heat of vaporisation, because the pressure drop and hence the pumping cost will be very high. it cannot be recovered by distillation. its recovery cost by distillation may be prohibitatively high. it will decompose while recovering by distillation.

its recovery cost by distillation may be prohibitatively high.

At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid __________ that in dry packed tower. is greater than is lower than is same as cannot be predicted as data are insufficient

is greater than

Molarity is defined as the number of gm moles of solute per __________ of solvent. litre kg gm c.c

litre

The value of Lewis number (Le = Sc/Pr) for air-water vapour system is around 1 0.24 3.97 600

An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii) less number of trays are required. composition of the residue remains unchanged. more number of trays are required but the residue composition remains unchanged. more number of trays are required and the residue composition is more dilute in methanol.

less number of trays are required.

The partial pressure distribution of an ideal gas diffusing through another stagnant ideal gas at steady state follows a/an __________ law. exponential parabolic linear cubic

exponential

Which of the following binary systems is an example of a maximum boiling azeotrope ? Water-hydrochloric acid. Acetone-carbon disulphide. Water-ethyl alcohol. n-heptane-n-octane.

Water-hydrochloric acid.

(NRe . NSc) is termed in mass transfer operation as the __________ number. Stanton Sherwood Peclet none of these

Peclet

The binary diffusivity in gases and liquids vary respectively as T^3/2 and T T and T^3/2 √T and T^3/2 T^3/2 and √T

T^3/2 and T

Pick out the correct statement. The slope of the stripping line is always less than unity. For a given separation in a binary distillation column, with increase in reflux ratio (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux. Kremsor-Brown-Souder's equation is used to calculate the efficiency of a plate tower.

In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux.

Pick out the correct statement. Dialysis process is used for the production of fresh water from brine. Electrodylsis is used in the manufacture of NaOH. Electrodylsis is used for the refin-ning/purification of petrol. both (b) and (c).

Electrodylsis is used in the manufacture of NaOH.

Pick out the correct statement. Bound moisture is removed during constant rate drying period. Free moisture is removed during falling rate drying period. The sum of free moisture and equilibrium moisture in a solid is called the critical moisture. The driving force for mass transfer in a wet solid is its free moisture content.

The driving force for mass transfer in a wet solid is its free moisture content.

Very tall packed towers are divided into series of beds to reduce the overall pressure drop avoid channelling reduce liquid hold-up avoid flooding

avoid channelling

Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture. unbound free critical bound

free

With increase in temperature, the solubility of gases in liquids, at fixed pressure increases decreases remains same either (a) or (b), depends on the system

decreases

In most of the vacuum crystalliser, vacuum is generally produced by means of a suction pump compressed air jet steam jet ejector with a barometric condenser none of these

steam jet ejector with a barometric condenser

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 greater degree of separation with a fixed number of trays increased reboiler load increased reflux ratio None of these.

increased reflux ratio

__________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids. Watted wall Packed Plate Spray

Plate

Deairation (removal of O2) of water is done by rectification absorption ion-exchange adsorption

ion-exchange

Make up water is supplied during cooling tower operation to compensate for water losses due to evaporation blowdown entrainment all (a), (b)&(c)

all (a), (b)&(c)

Pick out the wrong statement. The mole fraction of solute is directly proportional to the molality of a 'dilute' solution. For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is nonlinear in the case of steady state unimolal unidirectional diffusion. Azeotropes obey Raoult's law at all temperature. The relative volatility of a binary mixture at the azeotropic composition is 1.

Azeotropes obey Raoult's law at all temperature.

A minimum boiling azeotrope is exemplified by toluene-benzene acetone-carbon disulphide water-isobutyl alcohol none of these

acetone-carbon disulphide

Which of the following solutions will follow Raoult's law most closely ? A solution of benzene, toluene and oxylene. 35% solution of camphor in water. 35% solution of NH3 in water. A solution of polar organic compounds (not of homologs of a series).

A solution of benzene, toluene and oxylene.

Use of raschig rings in place of crushed stones as packing in packed beds (other things being same) increases pressure drop, increases surface area. increases pressure drop, decreases surface area. decreases pressure drop, increases surface area. decreases pressure drop, decreases surface area.

decreases pressure drop, increases surface area.

The assumption made in Elis method in distillation is that enthalpy concentration lines of vapor and liquid are parallel straight both parallel and straight neither parallel nor straight

both parallel and straight

As complete saturation of an adsorbent is approached, the differential heat of adsrop-tion approaches that of normal condensation. integral heat of adsorption. zero. none of these.

that of normal condensation.

Absorption with chemical reaction' is involved in the removal of carbon dioxide from gaseous stream using alkaline solution. benzol from coke oven gas using solar oil/wash oil. ammonia from coke oven gas using refrigerated water. tar from coke oven gas in primary gas coolers using chilled water.

carbon dioxide from gaseous stream using alkaline solution.

The-relative volatility for separation of a non-ideal binary mixture by distillation should be 0 1 > 1 < 1

> 1

Pick out the wrong statement: Reboiler is not used in open steam distillation. The separation of solutes of different molecular sizes in a liquid solution by use of a suitable membrane is called dialysis. Freeze drying is used for the drying of fish. Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition.

Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition.

In paper industry, paper is dried in a __________ dryer. tunnel heated cylinder conveyor festoon

heated cylinder

Pick out the wrong statement. Critical moisture content is not a property of the material itself. A sharp increase in pressure drop gives an indication of the flooding in a distillation column. Separation of components is not possible in liquid extraction, if selectivity is unity. Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum.

Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum.

Only small amount of evaporation of water produces large cooling effects because of its large latent heat low viscosity small latent heat none of these

large latent heat

The most common packing used in industrial operations is __________ rings. raschig lessing cross-partition single spiral

raschig

When the feed to a distillation column is a saturated liquid, slope of the feed line is zero unity infinity none of these

infinity

Leaching of sugar from sugar beets is done by hot water hexane dilute H2SO4 lime water

hot water

Absorption factor method is used to calculate the number of ideal stages, when operating line lies above the equilibrium line. operating line lies below the equilibrium line. both operating and equilibrium lines are parallel. pressure drop in the column is very high.

both operating and equilibrium lines are parallel.

Flights in a rotary dryer are provided to lift and shower the solids thus exposing it thoroughly to the drying action of the gas. reduce the residence time of solid. increase the residence time of the solid. none of these.

lift and shower the solids thus exposing it thoroughly to the drying action of the gas.

If f = moles of vapour present per mole of feed, then the slope of feed line is (Mcabe-Thiele method) 1-f/f -(f-1)/f -1/f -f/1-f

-1/f

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 the system comprises of partially mis-cible liquids. the system comprises of miscible liquids. the system comprises of an azeotrope. on heating, a vapor phase will appear ; while on cooling, a solid phase will appear.

on heating, a vapor phase will appear ; while on cooling, a solid phase will appear.

The rate of mass transfer is not dependent upon the degree of dispersion of one fluid in the other. interfacial surface exposed between the phases. both (a) & (b). none of these.

none of these.

At equilibrium the concentration of water in vapour phase (C*)in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is 0.0 0.2 0.4 1.0

0.4

Dry bulb temperature of unsaturated air is more than its __________ temperature. dew point wet bulb both 'a' & 'b' neither 'a' nor 'b'

both 'a' & 'b'

For the case of flow of air past a wet bulb thermometer (air water vapour system), the approximate value of h2/ky.Cz is around 0.60 0.24 1 0.72

The reciprocal of stripping factor is termed as selectivity index relative volatility absorption factor Murphree efficiency

absorption factor

Ponchan-Savarit method analyses the fractional equipment based on enthalpy balance only. material balance only. both enthalpy and material balances. the assumption of constant molaloverflow.

both enthalpy and material balances.

The binary diffusivity in gases at atmospheric conditions is about 10-9 cm/sec 10-1 cm2/sec 10-3 sec/cm 10-4 cm2/sec2

10-1 cm2/sec

Percentage saturation is __________ the relative saturation. always smaller than always greater than not related to none of these

always smaller than

In case of a desorber (stripper), the operating line always lies above the equilibrium curve. operating line always lies below the equilibrium curve. temperature remains unaffected. temperature always increases.

operating line always lies below the equilibrium curve.

What is the reflux ratio at total reflux ? Zero Infinity Unity Data insufficient

Infinity

Under conditions of flooding in packed tower, the gas pressure drop decreases rapidly increases rapidly remains constant is maximum

is maximum

For achieving rapid drying rate in a spray dryer, the diameter of the particles in the feed should be in the range of __________ microns (1 mm = 1000 microns). 1-5 10-60 200-300 > 500

10-60

For absorbing a sparingly soluble gas in a liquid gas side mass transfer co-efficient should be increased. liquid side mass transfer co-efficient should be increased. liquid side mass transfer co-efficient should be decreased. mass transfer co-efficient must be kept constant.

liquid side mass transfer co-efficient should be increased.

The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or "outgassed" adsorbent to from a definite concentration of adsorbate is called its integral heat of adsorption. heat of wetting. differential heat of adsorption. heat of normal condensation.

integral heat of adsorption.

The minimum number of theoretical plates is required for achieving a given separation in distillation column with ____. no reflux total reflux zero reflux ratio minimum reflux ratio

total reflux

A good solvent used for absorption should not have very high viscosity vapor pressure freezing point all (a), (b) & (c)

all (a), (b) & (c)

In a counter-current liquid extractor both liquids flow at fixed rate. both liquids can have any desired flow rate. only one of the liquids may be pumped at any desired rate. liquid's flow rate depends upon the temperature and pressure.

only one of the liquids may be pumped at any desired rate.

Which of the following is an undesirable property for an absorbing solvent ? Low vapour pressure Low velocity Low freezing point None of these

None of these

The wetted wall tower is used to determine individual mass transfer co-efficient (M.T.C.) in gaseous system. M.T.C. of individual components in a liquid-liquid system. M.T.C. of liquid in liquid-gas system. the overall M.T.C. of the system.

individual mass transfer co-efficient (M.T.C.) in gaseous system.

Weight of 1 m3 of humid air as compared to 1 m3 of dry air, under the same conditions, is less more same unpredictable

less

Positive deviation from Raoult's law means a mixture whose total pressure is greater than that computed for ideality. less than that computed for ideality. less than the sum of the vapour pressure of the components. none of these.

greater than that computed for ideality.

With increase in gas rate, the number of transfer units, NtoG, for a fixed degree of absorption by a fixed amount of solvent increases decreases decreases linearly remains unaffected

increases

Schmidt number is given by μ/ρD_AB Re.Pe Sh x Pe Re/Pe

μ/ρD_AB

Prandtl number for water at 20°C is about 7 70 0.7 150.

Boiling point diagram is not affected by pressure. affected by pressure. a plot of temperature vs. liquid composition. a plot of temperature vs. vapour composition.

affected by pressure.

When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system, as the acetone concentration increases, the solubility curves approach each other. both the phases become identical at a particular common point on both the solubility curves called the plait point. the distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption terminates on the x = y diagonal at the concentration of the plait point. all (a), (b) and (c).

all (a), (b) and (c).

Steam distillation is used to reduce the number of plates. avoid thermal decomposition of a component. increase the efficiency of separation. increase the total pressure of distillation.

avoid thermal decomposition of a component.

Freundlich equation applies to the adsorption of solute from dilute solutions, over a small concentration range. gaseous solutions at high pressure. concentrated solutions. none of these.

dilute solutions, over a small concentration range.

For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement. no change in theoretical marginal decrease in the number of major decrease in the number of none of these

marginal decrease in the number of

The apex of an equilateral-triangular coordinate (in ternary liquid system) represents a/an pure component binary mixture ternary mixture insoluble binary system

pure component

The diffusivity (D) in a binary gas mixture is related to the pressure (P) as D ∝ P^0.5 D ∝ 1/P^0.5 D ∝ 1/P D ∝ 1/P^1.5

D ∝ 1/P

A slurry is to be dried to produce flaky solid. Which dryer would you recommend ? Spray dryer Drum dryer Rotary dryer Dielectric dryer

Spray dryer

Which of the following psychrometric processes is followed by water vapour laden unsaturated air, when it is passed through solid or liquid adsorbent ? Cooling and dehumidification. Heating and dehumidification at almost constant wet bulb temperature. Dehumidification with dry bulb temperature remaining constant. None of these.

Heating and dehumidification at almost constant wet bulb temperature.

In gas-liquid contact operation, the number of ideal stages, N=(Xa-Xb)/(Xb-Xb*) . This is true when the stripping factor 'S' is S > 1 S < 1 S = 1 S = ∞

S > 1

The cooling effect in a cooling tower can not be increased by increasing the air velocity over the wet surfaces. reducing the humidity of entering air. lowering the barometric pressure. none of these.

none of these.

The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through non-diffusing gas 'B' is 1 ∞ 0.5 2

The humid volume may be increased by increasing the temperature at constant humidity. humidity at constant temperature. both (a) and (b). neither (a) nor (b).

both (a) and (b).

Pick out the wrong statement Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance. In case of gas absorption, HETP is equal to HTU, when both the operating line & the equilibrium lines are parallel. Hatta number is important in case of gas absorption with chemical reaction. In actual practice, absorption is an en-dothermic process, while stripping is an exothermic process.

In actual practice, absorption is an en-dothermic process, while stripping is an exothermic process.

When the mixture to be distilled has a very high boiling point and the product material is heat sensitive, the separation technique to be used is __________ distillation. continuous steam azerotropic none of these

steam

Large scale drying of wheat is done in a __________ dryer. fluidised bed spouted bed tray vacuum rotary

spouted bed

Azeotropic distillation is employed to separate constant boiling mixture. high boiling mixture. mixture with very high relative volatility. heat sensitive materials.

constant boiling mixture.

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 ) √T T T2 T3

At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes 1 0 ∞ none of these

∞

Use of natural draft cooling tower is practised, when the air has low humidity temperature both 'a' & 'b' neither 'a' nor 'b'

both 'a' & 'b'

Pressure drop through plate tower as compared to that through packed tower, for the same duty will be less more equal either (a) or (b); depends on the packing height

Dimension of mass diffusivity is the same as that of kinematic viscosity dynamic viscosity surface tension pressure

kinematic viscosity

Dorr thickener is an equipment used for classification sedimentation clarification leaching

sedimentation

Steam distillation is used to separate azeotropes. high boiling substances from nonvolatile impurities. heat sensitive materials. mixtures of low relative volatility.

high boiling substances from nonvolatile impurities.

In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed q > 1 q < 1 q = 1 q = 0

q = 1

Which of the following is an undesirable property in a tower packing ? Large surface per unit volume. Large free cross-section. Low weight per unit volume. Large weight of liquid retained.

Large weight of liquid retained.

Water entrained by circulating air in cooling towers is termed as drift blow down vapor load none of these.

drift

A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m x 1m x 1cm flat sheet of the same material is to be dried from one side only.Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is 1000 1500 2000 2500

1000

With increase in temperature, the rate of leaching increases, because the diffusivity of solute increases. viscosity of solvent decreases. thermal conductivity of solute increases. none of these.

diffusivity of solute increases.

Humidity chart is useful for the solution of problems concerning condensation, vaporisation and air conditioning. At a given dry bulb temperature, value of humidity obtained from the humidity chart directly, is in terms of __________ humidity. molal relative percentage none of these

molal

The Kundsen diffusivity is proportional to (where, T = absolute temperature) √T T2 T T4

√T

In case of constant underflow extraction operation, the __________ at all solute concentration. solids are drained to the same extent ratio of the insoluble to solution is constant both(a) & (b) neither (a) nor (b)

both(a) & (b)

In an absorption coloumn, the flooding velocity for random packing is __________ that for stacked/regular packing. greater than smaller than equal to either (a), or (b) ; depends on the type of packing

smaller than

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.) Kc = Kp = Km Kc = Kp/RT = Km . RT/P Kc = Kp . RT = Km . RT/p none of these

Kc = Kp . RT = Km . RT/p

With increase in temperature, the leaching rate increases because of the increased diffusivity. decreased viscosity of liquid. both (a) and (b). neither (a) nor (b).

both (a) and (b).

Leaching of uranium ore and gold ore is done in centrifugal extractor Pachuka tanks Bollman extractor none of these

Pachuka tanks

Blowdown in a cooling tower means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities. increases the scale forming tendencies of water. is undesirable. all (a), (b) & (c).

means discarding a small fraction of circulating water to prevent and limit the concentration of salt and impurities.

During constant rate period, the rate of drying decreases with the decrease in air temperature increase in air humidity both (a) and (b) neither (a) nor (b)

both (a) and (b)

Antibiotics are best handled in a Podbielniak extractor. sieve tray contractor. rotating disc contactor. pulsed column extractor.

Podbielniak extractor.

The fixed cost of a distillation column at minimum reflux ratio is minimum infinite optimum none of these

infinite

__________ extractor uses centrifugal force for separating the two phases. Treybal Schiebel Podbielniak None of these

Podbielniak

In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of 1.5 -0.6 -1.5 0.6

-1.5

Pick out the wrong statement. Mechanical agitation is required, if the system has low interfacial tension. Seive tray towers are generally used for systems having low interfacial tension. When Henry's law constant is very small, then the mass transfer rate is controlled by the gas film resistance. Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers.

Mechanical agitation is required, if the system has low interfacial tension.

Acetic acid will be most economically separated from a dilute solution of acetic acid in water by solvent extraction continuous distillation evaporation absorption

solvent extraction

Design calculation for multiple component distillation is done by Ponchon-Savarit method Mccabe-Thiele method enthalpy concentration method tray to tray calculations.

tray to tray calculations.

To get high tray efficiency interfacial surface between liquid and gas phase should be large. time of contact between the two phases should be less. gas velocity should be very low. liquid entrainment should be severe.

interfacial surface between liquid and gas phase should be large.

The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which D is the diffusivity of solute, is D/a D/2a proportional to D dependent on the Reynolds number

dependent on the Reynolds number

Pick out the wrong statement. Generally for physical adsorption, a gas of higher molecular weight is adsorbed in preference to a gas of low molecular weight. high critical temperature is adsorbed in preference to a gas of low critical temperature. low volatility is adsorbed in preference to a gas of high volatility. none of these.

none of these.

In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in reducing the axial mixing. increasing the rate of extraction. maintaining the concentration difference between the two phases. all 'a', 'b' & 'c'.

all 'a', 'b' & 'c'.

Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when extracting solvent is cheaply & abundantly available. one of the liquid components is heat sensitive. viscosity of liquid components is very high. one of the liquid components has very high affinity towards the solvent.

one of the liquid components has very high affinity towards the solvent.

Inside the distillation column, the driving force for the vapour flow is the pressure drop. liquids are not always at their bubble points. pressure increases gradually from bottom to the top of the column. none of these

driving force for the vapour flow is the pressure drop.

Diffusivity in concentrated solutions differs from that in dilute solutions, because of the changes in viscosity with concentration. degree of ideality of the solution. both (a) and (b). neither (a) nor (b).

both (a) and (b).

Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. increases decreases does not affect exponentially increases

decreases

Which of the following is not a continuous drier ? Drum drier Spray drier Tunnel drier Tray drier

Tray drier

Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is insoluble in the liquid soluble in the liquid non-ideal in nature at a fixed temperature

insoluble in the liquid

__________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid. Dew point Bubble point Dry bulb temperature Wet bulb temperature

Dew point

Rate of leaching increases with increasing temperature viscosity of solvent pressure size of the solid

temperature

An azeotropic mixture is a __________ mixture. binary ternary constant boiling point none of these

constant boiling point

Pick out the wrong statement. In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed. In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency. For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 x 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 x 10-2m/s. The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity.

For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 x 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 x 10-2m/s.

Molecular seives are regenerated by heating to __________ °C. < 150 200-330 > 500 > 1000

200-330

In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as Ri = Re/1-Re Ri = 1-Re/Re Ri = Re Ri = Re/1+Re

Ri = Re/1+Re

In a counter-current extractor, as the axial mixing increases, the extraction efficiency increases decreases remains unchanged depends on the pressure of the system

decreases

Heat sensitive materials like certain pharmaceuticals and food stuffs can be dried in a/an __________ dryer. indirect tray spray freeze none of these

freeze

In extractive distillation, solvent is added to alter the relative volatility of the mixture. of high volatility. present in overhead stream. of high viscosity to give high tray efficiency.

added to alter the relative volatility of the mixture.

Radioactive nuclear waste is treated in mixer-settler extractor rotating-disc contactor pulsed column extractor Bollman extractor

pulsed column extractor

Large scale drying of sugar is done in a __________ dryer. spouted bed tray rotary truck

rotary

__________ temperature is the steady state temperature attained by a small amount of liquid evaporating into a large quantity of unsaturated gas-vapor mixture. Dry bulb Wet bulb Dew point none of these

Wet bulb

The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid ) √T T T^1.5 T^3

__________ equation applies to diffusivities in liquids. Gilliland Hirschfelder Wilke and Chang none of these

Gilliland

A packed tower compared to a plate tower for a particular mass transfer operation incurs smaller pressure drop. allows installation of cooling coils. is less costly when built in large sizes/diameters. is more suitable, if suspended solids are present in fluid streams.

incurs smaller pressure drop.

Which of the following is the most commonly used leaching solvent in vegetable oil industry ? Phenol Hexane Furfurol Liquid SO2

Hexane

In an absorber, HETP does not vary with the flow rate of liquid flow rate of gas type and size of packing none of these

none of these

Large quantity of silica gel is normally dried in a __________ dryer. freeze through circulation rotary vacuum tray

through circulation

For the same system, if the same liquid used in an absorber is decreased, the tower height will increase decrease remain unaffected decrease or increase ; depends on the type of liquid

increase

Hydrogenation of oil is carried out in a/an __________ in Vanaspati manufacturing plant. agitated vessel sieve tray column bubble cap column packed tower

agitated vessel

Sides of equilateral-triangular co-ordinates (on which ternary liquid system is plotted) represent a pure component. a binary mixture. a ternary mixture. partially miscible ternary system.

a binary mixture.

In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when saturated feed is not used. an azeotrope forms. the latent heat of vaporisation of the more and less volatile components are greatly different. a total condenser is used.

a total condenser is used.

In an interphase mass transfer process, the lesser the solubility of a given solute in a liquid, the higher are the chances that the transfer process will be liquid phase resistance-controlled. gas phase resistance controlled. impossible. driven by a non-linear driving force.

gas phase resistance controlled.

As the reflux ratio decreases, the separation becomes more efficient. number of plates increases. column diameter increases. none of these.

number of plates increases.

Which of the following equipments is not used for gas dispersion ? Agitated vessels Bubble cap tray towers Perforated sieve tray towers Spray towers

Spray towers

One mole feed of a binary mixture of a given composition is flash vaporised at a fixed P and T. If Raoult's law is obeyed, then changing the feed composition would effect the product composition but not the fraction vaporised. the product composition as well as the fraction vaporised. the fraction vaporised but not the product composition. neither the product composition nor the fraction vaporised.

the fraction vaporised but not the product composition.

The equation, is for Na = Dab*Pt/RTZ(y1-y2) is for steady state equimolar counter diffusion Fick's first law of diffusion steady state diffusion for stagnant case liquid M.T.C. by penetration theory.

steady state equimolar counter diffusion

With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop decreases remains unchanged increases decreases exponentially

increases

The equation, is for Na = [Dab*Pt/RTZ.Pbm] * (y1-y2) is for Fick's second law of diffusion. stready state diffusion for stagnant case. liquid M.T.C. by Higbie penetration theory. none of these.

stready state diffusion for stagnant case.

Which of these columns incurs the lowest pressure drop ? Packed column (with stacked packing) Packed column (with dumped packing) Bubble plate column Pulse column

Packed column (with stacked packing)

In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase. gas liquid both (a) & (b) neither (a) nor (b)

liquid

If G = insoluble gas in gas stream and L = non-volatile solvent in liquid stream, then the slope of the operating line for the absorber is L/G G/L always < 1 none of these

L/G

Which of the following remains constant during evaporative cooling process with recirculated water supply ? Relative humidity Partial pressure of vapour Wet bulb temperature None of these

Wet bulb temperature

For stripping of a gas in a counter current stripper, the operating line lies above the equilibrium curve. lies below the equilibrium curve. can lie above or below the equilibrium curve. is always parallel to the equilibrium curve.

can lie above or below the equilibrium curve.

Which of the following same diameter columns gives lowest pressure drop per unit height ? Bubble-cap column Sieve-plate column Packed column (stacked) Randomly packed column

Packed column (stacked)

Diffusion in concentrated solutins differs from that in dilute solutions, because of the change in the __________ with the concentration of the solution. degree of ideality viscosity both 'a '& 'b' neither 'a' nor 'b'

both 'a '& 'b'

Stage efficiency in a leaching process depends on the time of contact between the solid and the solution rate of diffusion of the solute through the solid and into the liquid both (a) and (b) vapour pressure of the solution

both (a) and (b)

Operating velocity in a packed tower is usually __________ the flooding velocity. half twice equal to more than

half

The Knudsen diffusivity is dependent on the molecular velocity only. pore radius of the catalyst only. molecular mean free path only. molecular velocity and pore radius of the catalyst.

molecular velocity and pore radius of the catalyst.

Minimum possible diameter of a packed coloumn is decided mainly by the flooding gas viscosity liquid density liquid hold up

flooding

Solvent used in extractive distillation is of low volatility. forms a low boiling azeotrope. forms a high boiling azeotrope. does not alter the relative volatility of the original components.

forms a low boiling azeotrope.

Capacity of a rotary dryer depends on its r.p.m inclination with ground surface both (a) and (b) neither (a) nor (b)

both (a) and (b)

The cooling effect in a cooling tower can be speeded up by increasing the air velocity and area of exposed wet surface. reducing the barometric pressure. reducing the humidity of the air. all (a), (b) and (c).

all (a), (b) and (c).

When both the fluids flow concurrently in an absorber, the slope of the operating line is - ve + ve 1 -1

- ve

The percentage humidity is less than the relative humidity only at __________ percent humidity. zero hundred both zero and hundred none of these

both zero and hundred

Back-trapping in a distillation column increases tray efficiency. decreases tray efficiency. reduces pressure drop. is desirable, as it provides improved vapour-liquid contact.

decreases tray efficiency.

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. less than more than same as very much less

more than

Milk is dried usually in a __________ dryer. freeze spray tray rotary

spray

At a given equilibrium pressure, with increase in temperature, the concentration of adsorbed gas on solid adsorbant increases decreases remains unchanged increases exponentially

decreases

Which of the following adsorbent is used to decolourise yellow glycerine ? Silica gel Alumina Fuller's earth Activated carbon

Activated carbon

In a distillation column, with increase in the reflux ratio, the heat removed in the cooler increases. decreases. remains unaffected. and the heat required in reboiler decreases.

increases

Pick out the wrong statement. Constant pressure distillation can not separate an azeotropic mixture. Relative volatility of a binary mixture changes appreciably with the minor change in temperature. The relative volatility of a binary mixture at azeotropic composition is unity. Flash distillation is practised on wide spread scale in petroleum refinery.

Relative volatility of a binary mixture changes appreciably with the minor change in temperature.

Which of the following is not a unit of mass transfer co-efficient ? Moles transferred/(time)(area)(mole fraction) Moles transferred/(time)(area)(pressure) Moles transferred/(time)(area)(mass A/mass B) None of these

None of these

The falling rate period in the drying of a solid is characterised by increase in rate of drying. increasing temperatures both on the surface and within the solid. decreasing temperatures. none of these.

increasing temperatures both on the surface and within the solid.

In which of the following unit operations, the selectivity is an important parameter ? Distillation Solvent extraction Absorption None of these

Solvent extraction

Which of the following is an undesirable characteristic for the solvent used in gas absorption ? Low vapor pressure Low viscosity High gas solubility None of these

None of these

Which of the following equipments is not used for liquid dispersion ? Wetted wall towers Packed towers Venturi scrubbers Agitated vessels

Agitated vessels

Diameter of raschig rings used in packed tower in industry is normally around __________ inches. 2 8 12 18

The diffusion co-efficient in m2 /s. of acetic acid in benzene (liquid in liquid) is 2.09 x 10-4 2.09 x 10-5 2.09 x 10-9 2.09 x 10-12

2.09 x 10-9

Pick out the wrong statement. The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one. Sherwood number for flow in pipes can be expressed as the ratio of the concentration gradient at wall to the overall concentration difference. According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(b)P - 3, Q - 2 The z-component of the total mass flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz.

According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(b)P - 3, Q - 2

In case of non-ideal gases and liquids, the molal diffusivity varies inversely as the pressure. varies directly as the pressure. is independent of pressure. is equal to the volumetric diffusivity.

is independent of pressure.

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

p = P

__________ number indicates the ratio of the rates of the heat and mass transfer incase of a cooling tower. Sherwood Stanton Lewis Peclet

Lewis

The expression, y(1 - x)/x(1 - y) is for absorption factor relative volatility selectivity Murphree efficiency

relative volatility

In physical terms, Schmidt number means thermal diffusivity/mass diffusivity. thermal diffusivity/momentum diffusivity. momentum diffusivity/mass diffusivity. mass diffusivity/thermal diffusivity.

momentum diffusivity/mass diffusivity.

In case of liquids, the binary diffusivity is proportional to (where, T = temperature) T √T T2 1/T

The diffusivity, DAB (for component A diffusing in B) is equal to the diffusivity DBA (for component B diffusing in A) for a binary mixture of Newtonion liquids non-Newtonion liquids ideal gases real gases

ideal gases

Mass transfer co-efficient is directly proportional to DAB0.5, according to __________ theory. penetration surface renewal film none of these

penetration

Sand is dried in foundaries in a___drier. rotary fluidised bed vacuum spray

fluidised bed

Which of the following employs an accessory known as 'drift eliminator' ? Multiple effect evaporator. Mechanical draft cooling tower. Rotary dryer. Rotating disc contactor.

Mechanical draft cooling tower.

Pick out the correct statement. Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas. The 'Hatta number' is important in problems involving gas absorption without chemical reaction. For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion. Total reflux in case of distillation operation requires infinite number of plates for a binary system separation.

For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion.

Pick out the correct statement. For identical gas flow rates, less pressure drop occurs through a plate tower than through a packed tower. Plate column can handle greater liquid loads without flooding than packed column, but the liquid hold up is more in the case of plate column. For the same duty, plate columns weigh less than packed columns. all (a), (b) and (c).

all (a), (b) and (c).

Humid volume is the total volume in m3 of 1 kg of vapour laden gas at 1 atm. and room temperature. gas plus its accompanying vapour at 1 atm. and room temperature. gas plus its accompanying vapour at 1 atm. and gas temperature. vapour laden gas at 1 atm. and gas temperature.

gas plus its accompanying vapour at 1 atm. and gas temperature.

Diameter to height ratio for a rashig ring is 1 0.5 2 8

The equipment used in the extraction of highly corrosive radio active liquids is pulse column spray column mixer settler baffle tower

pulse column

Advantage of continuous drying over batch drying is that the drying cost per unit weight of dried product is less. product with more uniform moisture content is produced. equipment size required is smaller. all 'a', 'b' & 'c'

all 'a', 'b' & 'c'

With increase in temperature, the rate of extraction in leaching (solid-liquid extraction system) increases decreases remains unaffected increases Linearly

increases

In a packed bed absorption column, the channelling will be noted by the increase in flow rate. sharp drop in pressure drop. sharp rise in pressure drop. none of these.

sharp drop in pressure drop.

Gaseous diffusivity at atmospheric pressure is of the order of __________ cm2/second. 1 1 to 5 5 to 10 > 10

In liquid-liquid extraction, the number of phases at plait point is 1 2 3 4

In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer. The entire amount of C is transferred to solvent B. Less than 2 kg but more than 1 kg of C is transferred to solvent B. Less than 1 kg of C is transferred to B. No amount of C is tranferred to B.

The entire amount of C is transferred to solvent B.

The surface renewal frequency in Danckwerts' model of mass transfer is given by (KL: mass transfer co-efficient) √(KL2.DA) KL2.DA KL2/DA KL/DA2

√(KL2.DA)

If Rm is the minimum reflux ratio, the optimum reflux ratio may be around __________ Rm. 1.2 to 1.5 2.5 to 3 3 to 4 5

1.2 to 1.5

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. wet bulb temperature partial pressure of water vapor relative humidity none of these

wet bulb temperature

In case of absorption, both the operating and equilibrium lines will be straight for isothermal operation. dilute solutions. dilute solutions and isothermal operation. none of these.

dilute solutions and isothermal operation.

Mass transfer co-efficient varies as DAB0.5, according to the __________ theory. film surface renewal penetration none of these

surface renewal

For an absorber, both equilibrium and operating line will be straight for concentrated solution and non-isothermal operation. dilute solution and non-isothermal operation. dilute solution and isothermal operation. concentrated solution and isothermal operation.

dilute solution and isothermal operation.

Unsaturated air (with dry bulb and wet bulb temperatures being 45°C and 25°C respectively) is passed through a water spray chamber maintained at 23°C. The air will be cooled and humidified with wet bulb temperature decreasing. humidified at constant wet bulb temperature. dehumidified. none of these

humidified with wet bulb temperature decreasing.

Humid volume, at a given temperature is a/an __________ function of humidity. inverse exponential linear logarithmic

linear

The Schmidt number which is defined as, μ/ρ D, is the ratio of the momentum diffusivity to the mass dif-fusivity. thermal diffusivity to the mass diffusivity. momentum diffusivity to the thermal diffusivity. none of these.

momentum diffusivity to the mass dif-fusivity.

If f is defined as above, then which of the following applies to a feed at dew point ? f = 1 f < 1 f > 1 0 < f < 1

f = 1

Perforated plate towers are unique for solvent extraction because, they provide higher contact area. better contact of the phase. repeated coalescence & redispersion of the drop phase. none of these.

repeated coalescence & redispersion of the drop phase.

In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of __________ is zero. interface gas phase liquid phase all 'a', 'b' & 'c'

interface

Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. Sherwood number in mass transfer is analogous to Nusselt number in heat transfer. Prandtl number in heat transfer is analogous to Schmidt number in mass transfer. Reynolds number in mass transfer is analogous to Grashoff number in heat transfer. Reynolds number remains the same in both heat and mass transfer.

Reynolds number in mass transfer is analogous to Grashoff number in heat transfer.

The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is 0 ∞ -ve +ve

-ve

The individual mass transfer co-efficients (moles/m2 . s) 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 ? liquid side gas side interfacial both liquid and gas side

gas side

Pore size of the molecular seive 5A is __________ mm. 5 0.5 0.05 50

0.5

Swenson-Walker crystalliser is a __________ unit continuous batch semi-batch cooling (adiabatic)-cum-evaporation

continuous

According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the coloumn. 5 9 12 28

Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in decreased solute solubility. large minimum liquid to gas (L/G) ratio. large number of trays. all (a), (b) and (c).

all (a), (b) and (c).

With increase in temperature, the mutual solubility of two liquids _____. increases decreases remains unchanged decreases exponentially

increases

Pick out the wrong statement. In solvent extraction, the distribution co-efficient should be as large as possible for solvent economy. With increase in pressure, the solubility of gases in solvent increases at a fixed temperature. Decrease in Murphree plate efficiency is an indication of entrainment in distillation coloumn. The capacity of a distillation coloumn is maximum at total reflux.

The capacity of a distillation coloumn is maximum at total reflux.

The relative volatility of a binary mixture at the azeotropic composition is 1 > 1 0 ∞

Relative volatility varies with the concentration of component for an ideal solution. The relative volatity of a binary mixture may be defined as the ratio of vapor pressure of component 'A' to that of component 'B', when only vapor phase follows Raoult's law. only liquid phase obeys Dalton's law. liquid phase obeys Dalton's law and vapor phase obeys Raoult's law. Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law.

Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law.

Bound moisture is that liquid which exerts an equilibrium vapor pressure __________ that of the pure liquid at the given temperature. less than more than equal to either (o) or (b); depends on the solid

less than

Lewis number (Le) is Sc / Pr Pr x St Sh x Pr St x Sh

Sc / Pr

Which of the following is not a continuous leaching equipment ? Pachuka tank Kennedy extractor Bollman extractor Hydrocyclones

Pachuka tank

__________ extractor is used for the concentration of radioactive nuclear waste. Pulsed column Seive plate Mixer-settler Ballman

Pulsed column

Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture. free unbound equilibrium bound

equilibrium

All moisture in a non-hygroscopic material is the __________ moisture. free equilibrium unbound bound

unbound

Pick out the correct relationship. (where, Ri = internal reflux ratio Ro = external reflux ratio. ) (1 + Ro) = Ro/Ri (1 - Ro) = Ro/Ri (1 + Ri) = Ro/Ri (1 - Ri) = Ro/Ri

(1 + Ro) = Ro/Ri

Separation of __________ employs gaseous diffusion process. N2 and O2 from air isotopes of uranium isotopes of helium SO2 and air

isotopes of uranium

For water-ethanol system, the minimum reflux ratio is computed from the slope of the upper operating line that is tangent to the equilibrium curve. is computed from the intercept of the operating line. cannot be computed. is the optimum reflux ratio.

is computed from the slope of the upper operating line that is tangent to the equilibrium curve.

The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2/m3) 500 1200 900 800

500

Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysterisis. In such cases, the desorption equilibrium pressure is __________ that obtained for adsorption. lower than higher than same as either same or higher than

lower than

Experimental determination of __________ is done by wetted wall column method. diffusion co-efficient mass transfer co-efficient NTU none of these

mass transfer co-efficient

Pick out the wrong statement: Absorption factor is constant, when the equilibrium and operating lines are straight. In case of a stripper, the equilibrium curve is always below the operating line. In case of an absorber, the operating line is always above the equilibrium curve. In the absorption of low solubility gases, the liquid film is the controlling resistance.

In case of a stripper, the equilibrium curve is always below the operating line.

In liquid extraction, if the selectivity is unity, then separation of the constituents is the most effective. no separation will occur. amount of solvent required will be minimum. solvent flow rate should be very low.

no separation will occur.

Paper industry employs __________ driers. cylinder rotary spray fluidised bed

cylinder

Pick out the wrong statement pertaining to the cooling towers. In case of induced draft cooling tower, the fan is placed at the top of the tower. Effectiveness of forced draft cooling tower is reduced by the recirculation of the humid and hot discharged air. A natural draft cooling tower is recommended to be used, when the air humidity is low and air temperature is also low. Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature.

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

Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 x 10-3 kg mole/m2.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m2 .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is 5.6 x 10-4 8.5 x 10-4 5.6 x 10-3 8.5 x 10-3

8.5 x 10-4

Leaching of coarse solid lumps is also termed as decoction dissolution percolation agitation and settling

percolation

The main reason for dividing a tall packed tower into series of small towers is to minimise the overall pressure drop. avoid flooding. reduce liquid hold up. avoid channeling.

avoid channeling.

Co-current absorbers are usually used when the gas to be dissolved in the liquid is sparingly soluble highly soluble a pure substance a mixture

a pure substance

At what percentage (by volume) of alcohol composition, it forms an azeotrope with water ? 90 91.5 95 99

Measurement of the interfacial area of mass transfer is achieved easily & accurately in case of a __________ coloumn. spray packed bubble cap plate wetted wall

wetted wall

With the lowering of equiliDrium pressure, at a given temperature, the amount of ad-sorbate on the adsorbent increases. decreases. remains same. either (a) or (b), depends on the system.

decreases.

Mass transfer co-efficient is defined as Flux = Co-efficient/concentration difference. Co-efficient = Flux/concentration difference. Flux=concentration difference/co-effi-cient. none of these.

Co-efficient = Flux/concentration difference.

When an unsaturated air-water mixture is heated at constant pressure, then the partial pressure of water vapour increases. the specific humidity decreases. The relative humidity increases. the relative humidity decreases.

the relative humidity decreases.

At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is __________ percent. 100 0 50 between 0 and 100

In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is equal to the heat of formation of surface compound. equal to the heat of wetting. zero. called integral heat of adsorption.

equal to the heat of wetting.

Pick out the wrong statement: Change in barometric pressure does not affect the relative humidity. In case of a packed tower, the operating velocity is about half of the flooding velocity, generally. 'Elution' means the desorption of the adsorbed solute by a solvent. The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity.

The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity.

The value of L/mG ratio for economical absorption operation ranges from 0.5 to 0.8 0.8 to 1.2 1.25 to 2.0 2.5 to 3.5

1.25 to 2.0

Large scale usage of flash distillation is practised in soap manufacturing ammonia synthesis plant polymerisation industry petroleum refinning

petroleum refinning

High pressure at the bottom of a distillation tower handling heat sensitive materials results in _____. thermal decomposition of bottoms. increased relative volatility. erosion of the tower. very efficient operation.

thermal decomposition of bottoms.

Alcohol is dehydrated using __________ distillation. extractive azeotropic steam molecular

azeotropic

Separation of two volatile liquids by distillation makes use of their selectivity relative volatility solubility density difference

relative volatility

Dried finished product sampled from various parts of a __________ dryer exhibits non-uniformity in the moisture content. rotary tray freeze none of these

tray

__________ is used as an 'entrainer' for the separation of acetic acid-water mixture by distillation. Furfural Benzol Butyl acetate Hexane

Butyl acetate

Rotary dryers cannot handle __________ materials. free flowing dry sticky grannular

sticky

Pick out the correct statement. Diffusivity decreases with increase in temperature. Diffusivity increases with increase in molecular weight. Diffusivity increases with the size of the individual molecule. none of these.

none of these.

An example of elutioh is separation of uranium oxide from its ore by H2SO4 in a Pachuca tank. separation of sugar from sugar beet by hot water. dissolution of tannin out of tree barks by water. recovery of vegetable oils from seeds.

separation of uranium oxide from its ore by H2SO4 in a Pachuca tank.

The operating line for an absorber is curved, when plotted in terms of mole fractions mole ratios partial pressure mass fractions

partial pressure

Relative volatility does not change appreciably with the change in temperature vapour pressure of either component total pressure none of these

temperature

The dew point of a saturated gas phase equals the __________ temperature. gas room wet bulb none of these

gas

A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process ? Flow rate of inlet air Relative humidity of outlet air Humidity of inlet air Temperature of the solid

Temperature of the solid

For continuous drying of grannular or crystalline material, the dryer used is the __________ dryer. tunnel tray rotary none of these

rotary

In case of liquid-liquid binary diffusion, diffusivity of one constituent into another is not dependent on the temperature and pressure concentration nature of the constituents none of these

none of these

When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption. always lower than always higher than same as dependent on the system; can be either lower or higher than

always lower than

Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. bound unbound critical none of these

bound

For a binary mixture with low relative volatility, continuous rectification to get pure products will require low reflux ratio less number of trays small cross-section column high reflux ratio

high reflux ratio

The efficiency of a plate column will be maximum, when the flow is ideal __________ the plate. across above both (a) & (b) neither (a) nor (b)

both (a) & (b)

Heat load in a cooling tower means the amount of heat thrown away (KCal/hr.) by the cooling tower. is equal to the number of kg, of water circulated times the cooling range. both (a) & (b). neither (a) nor (b).

both (a) & (b).

Detergent solution is dried to a powder in a spray dryer spouted bed dryer tunnel dryer pan open to atmosphere

spray dryer

Which of the following mixtures does not form an azeotrope at atmosheric pressure? Water-alcohol Methyl alcohol-acetone Butyl acetate-water None of these

None of these

During bottling of cold drinks (e.g. Pepsi), the main resistance to mass transfer for the absorption of carbon dioxide in water lies in the gas film liquid film liquid-gas interface none of these

liquid film

The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by increasing the gas film co-efficient. increasing the liquid film co-efficient. increasing the total pressure. decreasing the total pressure.

increasing the gas film co-efficient.

Flooding results in high tray efficiency low tray efficiency high gas velocity good contact between the fluids

low tray efficiency

For the air water system under ambient conditions, the adiabatic saturation temperature and the wet bulb temperature are nearly equal, because water has a high latent heat of evaporation. Lewis number is close to unity. they are always equal under all circumstances. solubility of the components of air in water is very small.

water has a high latent heat of evaporation.

In an operating distillation column, the vapors and liquids are at their dew point and bubble point respectively driving force for the liquid flow is its specific weight. driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column. highest temperature is encountered at the top of the column.

driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column.

In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the range is 15°F. approach is 10°F. both (a) & (b). neither (a) nor (b).

both (a) & (b). Temperature range (T1 - T2) = 15°F. Temperature approach (T2 - tw) = 10°F. Wet-bulb temperature tw = 70°F.

The diffusivity (D) in a binary gas mixture is related to the temperature (T) as D ∝ T D ∝ T^0.5 D ∝ T^1.5 D ∝ T2

D ∝ T^1.5 Refer to Fuller et al.

For which of the following unit operations, Lewis number is of significance ? Adsorption Binary distillation Gas absorption Humidification

Humidification

Tray spacing in a distillation column of dia 10-12 ft. used in petroleum refinery may be around __________ inches. 5 30 60 100

If a1 and a2 are the relative volatilities when the pressure in the distillation column is 1 and 2 atm respectively. Pick out the correct statement. a1 = a2 a1 = 2a2 a1 = 0.5 a2 none of these

none of these

The dimension of diffusivity is same as that of the density molal concentration kinematic viscosity velocity head

kinematic viscosity

The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature. dew point wet bulb dry bulb none of these

none of these Must be adiabatic temp

Entrainer used in azeotropic distillation should form a low boiling azeotrope with one of the constituents of the mixture. form a new azeotrope of low relative volatility with one of the constituents of the mixture. have high latent heat of vaporisation. have high viscosity to provide high tray efficiency.

form a low boiling azeotrope with one of the constituents of the mixture.

In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapour, because temperature is less. total pressure is less. mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition. saturated steam is used for steam distillation.

mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition.

Pick out the wrong statement. The operating line always lies above the equilibrium solubility curve in case of a single component absorber. The operating line always lies below the equilibrium solubility curve in case of a single component stripper. The operating pressure in solvent extraction system should be below vapor pressures of all components. The solubility of a particular gas in ideal solution in any solvent is always the same.

The operating pressure in solvent extraction system should be below vapor pressures of all components.

Leaching of coffee from coffee beans is done by hot water hexane lime water dilute H2SO4 (hot)

hot water

For contacting a highly soluble gas with a liquid bubble the gas through liquid. spray the liquid on gas stream. either (a) or (b) would suffice. none of these.

bubble the gas through liquid.

During drying operation, it is easier to remove the __________ moisture. equilibrium critical unbound bound

unbound

With increase in solvent rate, the number of transfer units, NtoG, for a fixed degree of absorption from a fixed amount of gas increases decreases decreases linearly remains unaffected

decreases

Ion exchange process is similar to absorption adsorption extraction leaching

adsorption

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, composition of vapors and that of liquid do not vary throughout the column. reboiler load and condenser load are minimum. the top and bottom compositions are unchanged with and without total reflux. the top and bottom compositions correspond to the maximum enrichment available.

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

Dryer widely used in a textile industry is __________ dryer. festoon cylinder conveyor tunnel

conveyor

Solvent used in extractive distillation changes the relative volatility of the original components. should be of high volatility. should form azeotropes with the original components. all (a), (b) and (c)

changes the relative volatility of the original components.

Air at a particular humidity is heated in a furnace. The new dew point decreases increases depends on the extent of heating remain unchanged

increases

In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalant to a theoretical plate HTUOG = overall gas phase height of a transfer unit) straight parallel both (a) & (b) neither (a) nor (b)

both (a) & (b)

The vapour pressure exerted by the moisture contained in a wet solid depends upon the nature of the moisture. temperature. nature of the solid. all (a), (b) and (c).

all (a), (b) and (c).

The absorption factor is defined as (where, L = liquid flow rate, G = gas flow rate and, m = slope of the equilibrium line) L/mG G/mL mL/G LG/m

L/mG

Smoke is an example of solid dispersed in liquid solid dispersed in gas liquid dispersed in gas gas dispersed in liquid

solid dispersed in gas

Which of the following adsorbant is used in the refinning of sugar ? Bone charcoal Wood charcoal Silica gel Activated clay

Bone charcoal

Stacked packing compared to dumped packing provides poorer contact between the fluids. gives lower pressure drop. both (a) and (b). gives higher pressure drop.

both (a) and (b).

In McCabe-Thiele method of theoretical plate calculation for a distillation column, the operating lines of stripping and rectifying sections coincide with the diagonal at __________ reflux. total minimum operating maximum permissible

total