Q.1

For the same process conditions, the reflux ratio of an unlagged distillation column

  • decreases in winter
  • increases in winter
  • increases in summer
  • none of these
Q.2

In saturated gas, the

  • vapour is in equilibrium with the liquid at the gas temperature.
  • vapour is in equilibrium with the liquid at the room temperature.
  • partial pressure of vapour equals the vapour pressure of the liquid at room temperature.
  • none of these.
Q.3

With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature)

  • increases
  • remains unchanged
  • decreases
  • decreases linearly
Q.4

Steam distillation is used for separation of high boiling

  • substances from non-volatile impurities.
  • volatile impurity from still higher boiling substances.
  • both (a) and (b).
  • neither (a) nor (b).
Q.5

Nitrobenzene (boiling point = 210.6°C) is steam distilled at atm pressure.Nitrobenzene will distill off __________ °C.

  • at < 100
  • at > 210.6
  • between 100 and 210
  • none of these
Q.6

The relative saturation of an unsaturated mixture of gas and vapor is independent of the

  • nature of the vapor.
  • temperature of the mixture.
  • composition of the mixture.
  • none of these.
Q.7

With increase in the concentration of the adsorbate, the integral heat of adsorption

  • increases.
  • decreases.
  • remains unchanged.
  • may increase or decrease ; depends on the type of adsorbate.
Q.8

If the amount of the steam used in steam distillation is increased, the temperature of distillation

  • increases
  • decreases
  • remains unchanged
  • depends on relative volatility
Q.9

During the constant rate period of drying of a solid,

  • increased air humidity decreases the rate of drying.
  • increasing the air temperature decreases the drying rate.
  • surface evaporation of unbound moisture occurs.
  • none of these.
Q.10

(NSh/NRe.NSc) is termed in mass transfer operation as the

  • Stanton number
  • Peclet number
  • thermal diffusivity
  • momentum diffusivity
Q.11

Refractory bricks are usually dried in a __________ dryer.

  • tray
  • tunnel
  • conveyor
  • festoon
Q.12

For absorbers, high pressure drop results in

  • increased efficiency.
  • decreased efficiency.
  • high operating cost.
  • better gas liquid contact.
Q.13

An ideal tower packing should not

  • have low weight per unit volume.
  • have large surface area per unit volume.
  • have large free cross-section.
  • hold up large amount of liquid in the packing.
Q.14

An alkaline solution is used to reduce the concentration of carbon dioxide in a stream fromto 0.by absorption with irreversible chemical reaction. The overall number of transfer units based on gas phase is

  • 9.21
  • 4.605
  • 100
  • 0.001
Q.15

Equilibrium-moisture curves of different solids

  • are different
  • are same
  • depend on the humidity of the gas
  • none of these
Q.16

In the absorption of ammonia in water, the main resistance to absorption is by the __________ phase.

  • liquid
  • gas
  • both (a) & (b)
  • neither (a) nor (b)
Q.17

__________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction.

  • Packed
  • Bubble
  • Spray
  • Tray
Q.18

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

  • increase
  • decrease
  • remains same
  • depend on saturated boiling point; may increase or decrease
Q.19

Rose oil is extracted from rose leaves using __________ distillation.

  • high pressure
  • low pressure
  • extractive
  • steam
Q.20

Pick out the wrong statement.

  • With decrease in feed temperature, the number of plates required for binary distillation decreases for a given L/V ratio.
  • 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.
  • Natural draft cooling towers are made of ferro-concrete and its cross-section is wider at the bottom.
  • Vanderwall adsorption is also called chemisorption.
Q.21

The adiabatic saturation curve for a vapour-gas mixture is

  • straight line.
  • slightly concave upward.
  • slightly concave downward.
  • none of these.
Q.22

Small dia distillation column can be a

  • packed column
  • sieve tray
  • bubble cap
  • any of these
Q.23

HETP is numerically equal to HTU, only when the operating line

  • lies below the equilibrium line.
  • lies above the equilibrium line.
  • and equilibrium lines are parallel.
  • is far from the equilibrium line.
Q.24

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.

  • Condenser and reboiler loads are the same in both the cases.
  • Reboiler load is the same in both the cases but condenser load is higher in case (ii).
  • Condenser load is the same in both the cases but reboiler load is higher in case (ii).
  • Both condensor and reboiler loads are higher in case (ii) as compared to case (i).
Q.25

Azeotropism for ethyl alcohol-water system disappears by

  • increasing temperature
  • decreasing pressure
  • increasing pressure
  • no means
Q.26

Drying of refractory is normally carried out in a __________ dryer.

  • open pan
  • tray
  • rotary vacuum
  • truck/tunnel.
Q.27

For absorbers, high pressure drop results in

  • increased efficiency.
  • decreased efficiency.
  • high operating cost.
  • better gas liquid contact.
Q.28

The 'shanks system' of leaching (i.e., counter-current multiple contact leaching) is used for

  • recovery of tannis from the tree barks and woods.
  • leaching sodium nitrate from Chilean nitrate bearing rock.
  • both (a) and (b).
  • neither (a) nor (b).
Q.29

Penetration model (theory) for mass transfer was enunciated by

  • Danckwerts
  • Toor and Marchello
  • Higbie
  • Kissinevskii
Q.30

For turbulent mass transfer in pipes, the Sherwood number depends on the Reynolds number as

  • Re0.33
  • Re0.53
  • Re0.83
  • Re
Q.31

At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation.

  • operating
  • total
  • minimum
  • maximum permissible
Q.32

Raschig ring made of procelain cannot be used for treating concentrated

  • hydrochloric acid
  • nitric acid
  • alkalis
  • sulphuric acid
Q.33

For a distillation column operating at minimum reflux, the

  • concentration of liquid and vapour leaving a plate will be same.
  • reflux ratio will be maximum.
  • number of plates required will be maximum.
  • none of these.
Q.34

Hypersorption refers to a __________ process.

  • fixed bed absorption
  • moving bed absorption
  • fixed bed adsorption
  • moving bed adsorption
Q.35

At what value of reflux ratio, number of theoretical plates in a distillation column is minimum ?

  • 0
  • 1
  • < 1
Q.36

Pick out the wrong statement.

  • Cellulose acetate membranes are used in dialysis process.
  • 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.
  • 'Cascade' means a group of stages interconnected so that various streams flow from one to another.
  • Zirconia probe is used for the humidity measurement.
Q.37

The value of NA/(NA + NB), for steady state equimolal counter diffusion of two gases 'A' and 'B' is

  • 1
  • 0.5
  • 2
Q.38

If mass diffusivity in a mixture is equal to the thermal diffusivity, then the Lewis number is

  • 0
  • 1
  • < 1
  • > 1
Q.39

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.kPa and 19.kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is

  • 0.048
  • 0.079
  • 0.122
  • 0.152
Q.40

Steady state equimolal counter diffusion occurs in case of

  • leaching
  • absorption
  • binary phase distillation
  • liquid-liquid extraction
Q.41

Degree of freedom for leaching and solvent extraction process is

  • 1
  • 3
  • 0
  • 2
Q.42

Heat sensitive materials with very high latent heat of vaporisation may be economically separated using

  • liquid extraction
  • distillation
  • evaporation
  • absorption
Q.43

Surface renewal model of mass transfer was enunciated by

  • Toor and Marchello
  • Fick
  • Danckwerts
  • Stefan
Q.44

When the __________ the relative humidity of air decreases, despite an increase in the absolute humidity.

  • temperature rises
  • pressure rises
  • temperature falls
  • pressure falls
Q.45

The relative humidity of air decreases in-spite of an increase in the absolute humidity, when the

  • temperature rises.
  • pressure rises.
  • temperature falls.
  • pressure falls.
Q.46

Separation of a mixture of two gases by absorption in the liquid solvent depends upon the difference in their

  • viscosity
  • density
  • solubility
  • relative volatility
Q.47

H2S present in naphtha reformed gas is removed by absorbing with

  • ethanolamine
  • K2CO3
  • HCl
  • vacuum gas oil
Q.48

During constant rate drying period, vaporisation rate per unit drying surface area

  • decreases with time.
  • increases with time.
  • does not change with time,
  • does not affect the moisture content of the wet solid.
Q.49

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

  • M(Xo - XF)
  • M(Xo/XF)
  • M ln(Xo/XF)
  • MXo ln(Xo/XF)
Q.50

Batch tray dryers suffers from the disadvantage of

  • high maintenance cost.
  • non-uniform & low production rate.
  • high labour cost & low heat economy.
  • all 'a', 'b' & 'c'.
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