SEPPROC

Question 1

Which of the following solutions will follow Raoult’s law most closely?

Answer 1

A solution of benzene, toluene and oxylene.

Question 2

Boiling point diagram is

Answer 2

affected by pressure

Question 3

The ease of difficulty of separating components by distillation is determined by the

Answer 3

relative volatility

Question 4

Strictly speaking, the relative volatility of most ideal binary solution is

Answer 4

greatly affected by temperature

Question 5

When the relative volatility of two miscible components is close to 1.00, the components can be separated by

Answer 5

extractive distillation

Question 6

The physical separation of components in a miscible mixture by simultaneous evaporation and condensation is

Answer 6

distillation

Question 7

In a batch distillation, the boiling point of the distillate product compared to the residue is

Answer 7

lower

Question 8

Increasing the operating pressure of a distilling column

Answer 8

makes separation difficult

Question 9

One mole feed of a binary mixture of a given composition is flash vaporized at a fixed P and T. If Raoult’s law is obeyed, then changing the feed composition would effect

Answer 9

the fraction vaporized but not the product composition

Question 10

Steam distillation is used to

Answer 10

avoid thermal decomposition of a component.

Question 11

The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by

Answer 11

raising the temperature and lowering the total pressure

Question 12

In distillation, the cooled liquid stream returned to the column to a cool plate or stage is called

Answer 12

reflux

Question 13

In a distilling column, the highest pressure will be at

Answer 13

the bottom

Question 14

A heat transfer equipment to convert vapor to liquid is a/an

Answer 14

condenser

Question 15

A reboiler provides heat to the

Answer 15

the bottom of a distilling column

Question 16

The temperature in distilling column, from bottom to top

Answer 16

decreases

Question 17

The theoretical minimum reflux ratio in distillation column is attained if the column has

Answer 17

infinite number of plates

Question 18

If x co-ordinate of intersection point of feed line and rectifying sections operating line on equilibrium curve is same as the mole fraction of more volatile components in the feed, then the quality of feed is

Answer 18

saturated liquid

Question 19

As the reflux ratio decreases, the

Answer 19

number of plates increases

Question 20

In a distillation column, with increase in the reflux ratio, the heat removed in the cooler

Answer 20

increases

Question 21

Fenske’s equation for determining the minimum number of theoretical stages in distillation column holds good, when the

Answer 21

relative volatility is reasonably constant

Question 22

Inside the distillation column, the

Answer 22

driving force for the vapor flow is the pressure drop

Question 23

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

Answer 23

increased reflux ratio

Question 24

In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of

Answer 24

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

Question 25

Overall efficiency of the distillation column is

Answer 25

the ratio of number of ideal plates to actual plates

Question 26

Pick out the correct statement. a. Ponchon-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. b. A sharp decrease in pressure drop is an indication of flooding in a distillation column. c. Solvent used in extractive distillation should be of high volatility. d. Flash distillation is suitable for separating components which have very close boiling temperature.

Answer 26

Ponchon-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.

Question 27

Pick out the correct statement. a. The slope of the stripping line is always less than unity. b. 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. c. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux. d. Kremsor-Brown-Souder's equation is used to calculate the efficiency of a plate tower.

Answer 27

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

Question 28

Design calculation for multiple component distillation is done by

Answer 28

tray to tray calculations

Question 29

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

Answer 29

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

Question 30

In extractive distillation, solvent is

Answer 30

added to alter the relative volatility of the mixture

Question 31

Solvent used in extractive distillation

Answer 31

forms a low boiling azeotrope

Question 32

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

Answer 32

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

Question 33

Azeotropic distillation is employed to separate

Answer 33

constant boiling mixture

Question 34

The equilibrium liquid composition compared to the vapor composition in case of azeotropic mixture is

Answer 34

same

Question 35

The equilibrium liquid composition compared to the vapor composition in case of azeotropic mixture is

Answer 35

same

Question 36

Pick out the wrong statement. a. The mole fraction of solute is directly proportional to the molality of a 'dilute' solution. b. 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. c. Azeotropes obey Raoult's law at all temperature. d. The relative volatility of a binary mixture at the azeotropic composition is 1.

Answer 36

Azeotropes obey Raoult's law at all temperature.

Question 37

Pick out the system with minimum boiling azeotrope at 1 atm.

Answer 37

ethyl alcohol-water

Question 38

Which of the following binary systems is an example of a maximum boiling azeotrope?

Answer 38

water-hydrochloric acid

Question 39

A unit operation in which a soluble component is removed from an inert solid by a solvent which preferentially dissolves the soluble matter is known as

Answer 39

leaching

Question 40

A unit operation in which a soluble component is removed from an inert solid by a solvent which preferentially dissolves the soluble matter is known as

Answer 40

leaching

Question 41

The unit operation by which soluble components of a liquid mixture are dissolved in a liquid immiscible with the insoluble component is

Answer 41

solvent extraction

Question 42

Tea percolation employs

Answer 42

leaching

Question 43

Which of the following is the most commonly used leaching solvent in vegetable oil industry?

Answer 43

hexane

Question 44

Leaching of sugar from sugar beets is done using

Answer 44

hot water

Question 45

In a counter-current extractor, as the axial mixing increases, the extraction efficiency

Answer 45

decreases

Question 46

Bollman extractor

Answer 46

is used for extraction of oil from oilseed

Question 47

Acetic acid will be most economically separated from a dilute solution of acetic acid in water by

Answer 47

solvent extraction

Question 48

Liquid-liquid extraction is based on the differences in

Answer 48

solubility

Question 49

Radioactive nuclear waste is treated in

Answer 49

pulsed column extractor

Question 50

The solvent used in liquid extraction should not have high latent heat of vaporization, because

Answer 50

the pressure drop and hence the pumping cost will be very high.

Question 51

Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when

Answer 51

extracting solvent is cheaply & abundantly available.

Question 52

In a counter-current liquid extractor

Answer 52

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

Question 53

A coalescer in a mixer-settler liquid-liquid extraction column

Answer 53

all of these

Question 54

Antibiotics are best handled in a

Answer 54

pulsed column extractor

Question 55

Rose oil is extracted from rose leaves using distillation

Answer 55

steam distillation

Question 56

When the solvent dissolves very little of solute then

Answer 56

large quantity of solvent is required to extract the solute

Question 57

An ideal single stage extraction process is used to treat 100 mol/s of an organic feed solution. The solute concentration in this solution is to be reduced from 0.5 mol% to 0.1 mol%. A pure solvent S is used. To reduce the solvent requirement by half for the same separation

Answer 57

use another pure solvent S* whose partition coefficient is twice that of S

Question 58

The triangle whose one corner coincides with the enriching line and the outer corner is on the stripping line is called the

Answer 58

feed plate

Question 59

Flash distillation is suitable for the separation of components

Answer 59

having very wide boiling points.

Question 60

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

Answer 60

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

Question 61

Leaching of coarse solid lumps is also termed as

Answer 61

percolation

Question 62

In an operating distillation column, the

Answer 62

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

Question 62

Large scale usage of flash distillation is practiced in

Answer 62

petroleum refinning

Question 63

In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapor, because

Answer 63

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

Question 64

For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be

Answer 64

1

Question 65

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

Answer 65

Centrifugal extractor

Question 66

Total reflux in a distillation operation requires minimum

Answer 66

number of plates

Question 67

In batch distillation with constant reflux, overhead product composition __ with time.

Answer 67

decreases

Question 68

Raoult's law applies to the

Answer 68

solvents

Question 69

In distillation, overhead product contains

Answer 69

any number of components

Question 70

For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will

Answer 70

increase

Question 71

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

Answer 71

elutriation or elution

Question 72

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

Answer 72

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

Question 73

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)

Answer 73

less number of trays are required.

Question 74

Ponchan-Savarit method analyses the fractional equipment based on

Answer 74

both enthalpy and material balances.

Question 75

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.

Answer 75

steam

Question 76

The fixed cost of a distillation column at minimum reflux ratio is

Answer 76

infinite

Question 77

__ extractor uses centrifugal force for separating the two phases.

Answer 77

Podbielniak

Question 78

In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in

Answer 78

All of these (maintaining the concentration difference between the two phases, increasing the rate of extraction, reducing the axial mixing)

Question 79

Which of the following applies to a feed at dew point?

Answer 79

f = 1

Question 80

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

Answer 80

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

Question 81

The relative volatility of a binary mixture at the azeotropic composition is

Answer 81

1

Question 82

Which of the following is not a continuous leaching equipment?

Answer 82

Pachuka tank

Question 83

High pressure at the bottom of a distillation tower handling heat sensitive materials results in

Answer 83

thermal decomposition of bottoms.

Question 84

For a binary mixture with low relative volatility, continuous rectification to get pure products will require

Answer 84

high reflux ratio

Question 85

In steam distillation, the

Answer 85

product must be immiscible with water.