Q.1

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.
Q.2

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

  • 1
  • 0.5
  • 10
  • 0
Q.3

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
Q.4

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.
Q.5

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.
Q.6

Chemisorption (chemical adsorption) is

  • same as "Van der Waals" adsorption.
  • characterised by adsorption of heat.
  • an irreversible phenomenon.
  • a reversible phenomenon.
Q.7

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
Q.8

In distillation, overhead product contains

  • only one component
  • two components
  • any number of components
  • only saturated liquid
Q.9

In case of an ideal solution, the total vapor pressure varies __________ with the composition expressed as mole fraction,

  • inversely
  • linearly
  • exponentially
  • none of these
Q.10

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.
Q.11

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.
Q.12

It takes 6 hours to dry a wet solid frommoisture content to the critical moisture content of 15%. How much longer it will take to dry the solid tomoisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%).

  • 15 min
  • 51 min
  • 71 min
  • 94 min
Q.13

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

  • litre
  • kg
  • gm
  • c.c
Q.14

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.
Q.15

Agitator is provided in a crystalliser for

  • avoiding deposition on cooler surfaces.
  • formation of nuclei.
  • crystal growth.
  • all (a), (b) and (c).
Q.16

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.
Q.17

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).
Q.18

Air initially at3 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.
Q.19

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.
Q.20

In a solution containing 0.Kg mole of solute andkg of solvent, the molality is

  • 1
  • 0.50
  • 0.60
  • 2
Q.21

(NRe . NSc) is termed in mass transfer operation as the __________ number.

  • Stanton
  • Sherwood
  • Peclet
  • none of these
Q.22

On addition of solute in the solvent, the __________ of the solution decreases.

  • boiling point
  • freezing point
  • vapour pressure
  • both (b) and (c)
Q.23

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'.
Q.24

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
Q.25

With increase in pressure, the relative volatility for a binary system

  • increases.
  • decreases.
  • remains same.
  • either (a) or (b), depends on the system.
Q.26

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).
Q.27

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

  • 1
  • 0.24
  • 3.97
  • 600
Q.28

Very tall packed towers are divided into series of beds to

  • reduce the overall pressure drop
  • avoid channelling
  • reduce liquid hold-up
  • avoid flooding
Q.29

__________ diffusion is used for separating the isotopes of methane.

  • Thermal
  • Pressure
  • Concentration
  • Force
Q.30

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
Q.31

The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is

  • +ve
  • -ve
  • zero
  • none of these
Q.32

Separation of two or more components of a liquid solution can not be achieved by

  • fractional crystallisation
  • liquid extraction
  • absorption
  • evaporation
Q.33

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)
Q.34

Fenske equation determines the

  • maximum number of ideal plates.
  • height of the distillation column.
  • minimum number of theoretical plates.
  • optimum reflux ratio.
Q.35

The binary diffusivity in gases and liquids vary respectively as

  • T3/2 and T
  • T and T3/2
  • T and T3/2
  • T3/2 and T
Q.36

Which is the controlling factor for a drum drier?

  • Diffusion
  • Heat transfer
  • Both (a) and (b)
  • Neither (a) nor (b)
Q.37

Raoult's law applies to the

  • all liquid solutions
  • non-ideal solution only.
  • non-volatile solute.
  • solvents.
Q.38

Which of the following remains constant during sensible cooling process ?

  • Specific humidity
  • Partial pressure of vapour
  • Both (a) and (b)
  • Neither (a) nor (b)
Q.39

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).
Q.40

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.
Q.41

Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture.

  • unbound
  • free
  • critical
  • bound
Q.42

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.
Q.43

Ordinary diffusion process is also called __________ diffusion.

  • pressure
  • thermal
  • concentration
  • forced.
Q.44

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'
Q.45

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.
Q.46

Stefan's law describes the mass transfer by

  • diffusion
  • bulk flow
  • both 'a' & 'b'
  • neither 'a' nor 'b'
Q.47

Which of the following plays an important role in problems of simultaneous heat and mass transfer ?

  • Lewis number
  • Schmidt number
  • Prandtl number
  • Sherwood number
Q.48

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
Q.49

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.
Q.50

Physical absorption is

  • an irreversible phenomenon.
  • a reversible phenomenon.
  • accompanied by evolution of heat.
  • both (b) and (c)
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