8247 + Mcqs in Chemical Engineering Page 44 McqOptions

2151.	Removal of __________ exemplifies an adsorption unit operation.
A.	uranium from its ore
B.	water from petrol
C.	ammonia from coke oven gas
D.	mustard oil from mustard seed
Answer» C. ammonia from coke oven gas

Discussion

2152.	Can the efficiency of a plate in the distillation tower be greater than 100% ?
A.	Yes
B.	Normally not; but is possible if infinite number of plates are put.
C.	Never
D.	Yes ; if the reflux ratio is maximum.
Answer» D. Yes ; if the reflux ratio is maximum.

Discussion

2153.	With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________ , if the conduction and radiation through the solid are negligible.
A.	increases
B.	decreases
C.	remains same
D.	increases linearly
Answer» B. decreases

Discussion

2154.	To remove all the moisture from a wet solid it requires exposure to __________ air.
A.	perfectly dry
B.	highly humid
C.	high temperature
D.	none of these
Answer» B. highly humid

Discussion

2155.	The Hatta number is important in
A.	multicomponent distillation.
B.	binary distillation.
C.	gas absorption without chemical reaction.
D.	gas absorption with chemical reaction.
Answer» E.

Discussion

2156.	When a multistage tray tower uses a minimum reflux ratio, it implies
A.	infinite trays and maximum reboiler heat load.
B.	infinite trays and minimum reboiler heat load.
C.	minimum trays and minimum reboiler heat load.
D.	minimum trays and maximum reboiler heat load
Answer» B. infinite trays and minimum reboiler heat load.

Discussion

2157.	Pick out the wrong statement. Raoult's law does not apply, when the
A.	size of component molecules are not equal.
B.	attractive forces between like and unlike molecules in the solution are approximately equal.
C.	component molecules are nonpolar.
D.	chemical combination or molecular association between unlike molecules takes place in the formation of solution.
Answer» D. chemical combination or molecular association between unlike molecules takes place in the formation of solution.

Discussion

2158.	For gas absorption, low viscosity solvents are preferred, because of their
A.	better flow characteristics.
B.	low pumping pressure drop.
C.	rapid absorption rates.
D.	all (a), (b) and (c).
Answer» E.

Discussion

2159.	Water-ethyl alcohal solution can be concentrated (in respect of alcohal concentration) by __________ distillation.
A.	atmospheric
B.	vacuum
C.	high pressure
D.	none of these
Answer» C. high pressure

Discussion

2160.	L/mG is the expression for
A.	absorption factor
B.	Brinkman number
C.	slope of operating line in absorber
D.	slope of operating line in stripper.
Answer» B. Brinkman number

Discussion

2161.	Extraction of pencillin employs a __________ extraction coloumn.
A.	centrifugal
B.	packed
C.	plate
D.	None of these.
Answer» B. packed

Discussion

2162.	With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature)
A.	increases
B.	remains unchanged
C.	decreases
D.	decreases linearly
Answer» B. remains unchanged

Discussion

2163.	Which of the following parameters remains almost constant during adiabatic saturation of unsaturated air ?
A.	Dry bulb temperature
B.	Dew point
C.	Wet bulb temperature
D.	None of these
Answer» D. None of these

Discussion

2164.	Coffee is prepared from coffee beans by leaching with
A.	cold water
B.	hot water
C.	dilute hot caustic solution
D.	naphtha
Answer» C. dilute hot caustic solution

Discussion

2165.	Gaseous diffusion co-efficient increases with increase in the
A.	pressure
B.	temperature
C.	both (a) & (b)
D.	neither (a) nor (b)
Answer» C. both (a) & (b)

Discussion

2166.	If xD = overhead product molal composition and RD = reflux ratio, then slope and intercept of the operating line for rectifying section are respectively
A.	<img src="/_files/images/chemical-engineering/mass-transfer/287-102-1.png">
B.	<img src="/_files/images/chemical-engineering/mass-transfer/287-102-2.png">
C.	<img src="/_files/images/chemical-engineering/mass-transfer/287-102-3.png">
D.	<img src="/_files/images/chemical-engineering/mass-transfer/287-102-4u.png">
Answer» C. <img src="/_files/images/chemical-engineering/mass-transfer/287-102-3.png">

Discussion

2167.	At a fixed total pressure, humidity depends only on the
A.	partial pressure of vapour in the mixture.
B.	heat capacity of the vapour.
C.	density of the vapour.
D.	none of these.
Answer» B. heat capacity of the vapour.

Discussion

2168.	If moisture content of solid on dry basis is X, then the same on wet basis is
A.	<img src="/_files/images/chemical-engineering/mass-transfer/292-160-1.png">
B.	<img src="/_files/images/chemical-engineering/mass-transfer/292-160-2.png">
C.	<img src="/_files/images/chemical-engineering/mass-transfer/292-160-3.png">
D.	<img src="/_files/images/chemical-engineering/mass-transfer/292-160-4.png">
Answer» B. <img src="/_files/images/chemical-engineering/mass-transfer/292-160-2.png">

Discussion

2169.	Flash distillation is
A.	same as differential distillation.
B.	used for multicomponent systems like crude refining.
C.	same as simple distillation.
D.	most useful for handling binary systems.
Answer» C. same as simple distillation.

Discussion

2170.	__________ developed the film theory.
A.	Higbie
B.	Fick
C.	Ergun
D.	Levenspeil
Answer» B. Fick

Discussion

2171.	For absorbers, high pressure drop results in
A.	increased efficiency.
B.	decreased efficiency.
C.	high operating cost.
D.	better gas liquid contact.
Answer» D. better gas liquid contact.

Discussion

2172.	For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same.
A.	unsaturated surface
B.	constant rate
C.	both (a) and (b)
D.	neither (a) nor (b).
Answer» D. neither (a) nor (b).

Discussion

2173.	What is the degree of freedom of an absorption process in which only one component is transferred between phases ?
A.	3
B.	2
C.	4
D.	1
Answer» B. 2

Discussion

2174.	Sticky material can be dried in a __________ dryer.
A.	tray
B.	rotary
C.	fluidised bed
D.	none of these
Answer» B. rotary

Discussion

2175.	Langmuir equation is associated with
A.	leaching
B.	adsorption
C.	steam distillation
D.	multicomponent absorption.
Answer» C. steam distillation

Discussion

2176.	During the constant rate period of drying of a solid,
A.	increased air humidity decreases the rate of drying.
B.	increasing the air temperature decreases the drying rate.
C.	surface evaporation of unbound moisture occurs.
D.	none of these.
Answer» D. none of these.

Discussion

2177.	The commonly used solvent in supercritical extraction is
A.	methyl ethyl ketone.
B.	water.
C.	carbon tetrachloride.
D.	carbon dioxide.
Answer» E.

Discussion

2178.	Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture.
A.	unbound
B.	critical
C.	free
D.	bound
Answer» B. critical

Discussion

2179.	Inside the distillation columns, the
A.	highest temperatures is near the feed plate.
B.	driving force for the liquid flow is its weight.
C.	vapors are not always at their dew points.
D.	all (a), (b) and (c)
Answer» C. vapors are not always at their dew points.

Discussion

2180.	When the psychometric ratio is __________ then the adiabatic saturation temperature and wet bulb temperature becomes equal.
A.	1
B.	< 1
C.	> 1
D.
Answer» B. < 1

Discussion

2181.	Desirable value of absorption factor in an absorber is
A.	1
B.	< 1
C.	> 1
D.	0.5
Answer» D. 0.5

Discussion

2182.	Refractory bricks are usually dried in a __________ dryer.
A.	tray
B.	tunnel
C.	conveyor
D.	festoon
Answer» C. conveyor

Discussion

2183.	A mixture of 10% C6H6 vapour in air at 25 C and 750 mm Hg has a dew point of 20 C. Its dew point at 30 C and 700 mm Hg will be around __________ C.
A.	21.7
B.	20
C.	27.3
D.	18.7
Answer» E.

Discussion

2184.	Which of the following is not fixed by the process requirements, in the design of absorbers ?
A.	Flow rate of the entering gas.
B.	Composition of the entering liquid.
C.	Terminal concentrations of gas stream.
D.	None of these.
Answer» E.

Discussion

2185.	If the amount of the steam used in steam distillation is increased, the temperature of distillation
A.	increases
B.	decreases
C.	remains unchanged
D.	depends on relative volatility
Answer» C. remains unchanged

Discussion

2186.	During drying of a solid, the critical moisture content increases with
A.	decreased drying rate
B.	increased thickness of the solid
C.	increased drying rate
D.	both (b) and (c).
Answer» E.

Discussion

2187.	Priming in a distillation column
A.	results from very low gas velocity.
B.	is desirable from point efficiency consideration.
C.	is characterised by the presence of foam throughout the space between trays.
D.	reduces the overall pressure drop.
Answer» D. reduces the overall pressure drop.

Discussion

2188.	When the liquid over a plate is of uniform concentration, then
A.	Murphree efficiency > point efficiency.
B.	Murphree efficiency < point efficiency.
C.	Murphree efficiency = point efficiency.
D.	Murphree efficiency point efficiency.
Answer» D. Murphree efficiency point efficiency.

Discussion

2189.	In saturated gas, the
A.	vapour is in equilibrium with the liquid at the gas temperature.
B.	vapour is in equilibrium with the liquid at the room temperature.
C.	partial pressure of vapour equals the vapour pressure of the liquid at room temperature.
D.	none of these.
Answer» B. vapour is in equilibrium with the liquid at the room temperature.

Discussion

2190.	CO2 can be absorbed by
A.	hot cupric oxide
B.	heated charcoal
C.	cold Ca(OH)
D.	<sub>2</sub>
E.	alumina
Answer» C. cold Ca(OH)

Discussion

2191.	When the gas to be dissolved in liquid is a/an __________ then normally co-current adsorber are used.
A.	mixture of two gases
B.	pure gas
C.	ideal gas
D.	sparingly soluble gas
Answer» C. ideal gas

Discussion

2192.	Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number.
A.	Schmidt
B.	Sherwood
C.	Peclet
D.	Stanton
Answer» B. Sherwood

Discussion

2193.	If a two phase system is in physical equilibrium; then it means that, the
A.	escaping tendency of each component from the liquid phase to the vapor phase is exactly equal to that from vapor phase to liquid phase.
B.	temperature of the liquid phase is equal to that of the vapor phase.
C.	total pressure throughout the liquid phase is equal to that throughout the vapor phase.
D.	all (a), (b) and (c).
Answer» E.

Discussion

2194.	McCabe-Thiele method of binary distillation does not assume that the
A.	sensible heat changes are negligible compared with latent heat changes.
B.	molar latent heats of all components are equal.
C.	heat of mixing is negligible.
D.	none of these
Answer» E.

Discussion

2195.	For the same process conditions, the reflux ratio of an unlagged distillation column
A.	decreases in winter
B.	increases in winter
C.	increases in summer
D.	none of these
Answer» C. increases in summer

Discussion

2196.	(NSh/NRe.NSc) is termed in mass transfer operation as the
A.	Stanton number
B.	Peclet number
C.	thermal diffusivity
D.	momentum diffusivity
Answer» B. Peclet number

Discussion

2197.	An ideal tower packing should not
A.	have low weight per unit volume.
B.	have large surface area per unit volume.
C.	have large free cross-section.
D.	hold up large amount of liquid in the packing.
Answer» E.

Discussion

2198.	The temperature of water cooled in cooling tower is always __________ temperature of entering air.
A.	more than the wet bulb
B.	less than the wet bulb
C.	equal to the wet bulb
D.	equal to the dry bulb
Answer» B. less than the wet bulb

Discussion

2199.	Which of the following processes is followed by unsaturated air (with dry bulb temperature 12 C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40 C?
A.	Humidification only
B.	Heating only
C.	Both heating and humidification
D.	Evaporative cooling
Answer» D. Evaporative cooling

Discussion

2200.	The operating cost of a distillation column at minimum reflux ratio is
A.	minimum
B.	maximum
C.	infinite
D.	zero
Answer» B. maximum

Discussion

Explore topic-wise MCQs in Engineering.

Removal of __________ exemplifies an adsorption unit operation.

Can the efficiency of a plate in the distillation tower be greater than 100% ?

With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________ , if the conduction and radiation through the solid are negligible.

To remove all the moisture from a wet solid it requires exposure to __________ air.

The Hatta number is important in

When a multistage tray tower uses a minimum reflux ratio, it implies

Pick out the wrong statement. Raoult's law does not apply, when the

For gas absorption, low viscosity solvents are preferred, because of their

Water-ethyl alcohal solution can be concentrated (in respect of alcohal concentration) by __________ distillation.

L/mG is the expression for

Extraction of pencillin employs a __________ extraction coloumn.

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

Which of the following parameters remains almost constant during adiabatic saturation of unsaturated air ?

Coffee is prepared from coffee beans by leaching with

Gaseous diffusion co-efficient increases with increase in the

If xD = overhead product molal composition and RD = reflux ratio, then slope and intercept of the operating line for rectifying section are respectively

At a fixed total pressure, humidity depends only on the

If moisture content of solid on dry basis is X, then the same on wet basis is

Flash distillation is

__________ developed the film theory.

For absorbers, high pressure drop results in

For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same.

What is the degree of freedom of an absorption process in which only one component is transferred between phases ?

Sticky material can be dried in a __________ dryer.

Langmuir equation is associated with

During the constant rate period of drying of a solid,

The commonly used solvent in supercritical extraction is

Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture.

Inside the distillation columns, the

When the psychometric ratio is __________ then the adiabatic saturation temperature and wet bulb temperature becomes equal.

Desirable value of absorption factor in an absorber is

Refractory bricks are usually dried in a __________ dryer.

A mixture of 10% C6H6 vapour in air at 25 C and 750 mm Hg has a dew point of 20 C. Its dew point at 30 C and 700 mm Hg will be around __________ C.

Which of the following is not fixed by the process requirements, in the design of absorbers ?

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

During drying of a solid, the critical moisture content increases with

Priming in a distillation column

When the liquid over a plate is of uniform concentration, then

In saturated gas, the

CO2 can be absorbed by

When the gas to be dissolved in liquid is a/an __________ then normally co-current adsorber are used.

Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number.

If a two phase system is in physical equilibrium; then it means that, the

McCabe-Thiele method of binary distillation does not assume that the

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

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

An ideal tower packing should not

The temperature of water cooled in cooling tower is always __________ temperature of entering air.

Which of the following processes is followed by unsaturated air (with dry bulb temperature 12 C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40 C?

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