As the reflux ratio in a distillation column is increased from the minimum, the

Liquid flow increases while the vapor flow decreases for a system

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

With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent

Either (A) or (B), depends on the system

The cooling effect in a cooling tower cannot be increased by

Increasing the air velocity over the wet surfaces

Reducing the humidity of entering air

Lowering the barometric pressure

The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume ofquiescent liquid, in which „D’ is the diffusivity of solute, is

Dependent on the Reynolds number

In an absorption column, the flooding velocity for random packing is __________ that for stacked/regular packing.

Either (A), or (B); depends on the type of packing

122 + Mcqs in General Page 3 McqOptions

101.	As the reflux ratio in a distillation column is increased from the minimum, the
A.	Slope of the operating line in stripping section decreases
B.	Number of plates decreases very slowly first and then more and more rapidly
C.	Total cost first decreases and then increases
D.	Liquid flow increases while the vapor flow decreases for a system
Answer» D. Liquid flow increases while the vapor flow decreases for a system

Discussion

102.	In extraction, as the temperature increases, the area of heterogeneity (area covered by binodal curve)
A.	Decreases
B.	Increases
C.	Remains unchanged
D.	None of these
Answer» B. Increases

Discussion

103.	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))
A.	M(Xo - XF)
B.	M(Xo/XF)
C.	M ln(Xo/XF)
D.	MXo ln(Xo/XF)
Answer» E.

Discussion

104.	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 )
A.	500
B.	1200
C.	900
D.	800
Answer» B. 1200

Discussion

105.	A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is:
A.	0.54
B.	1.04
C.	1.24
D.	1.94
Answer» D. 1.94

Discussion

106.	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.)
A.	Kc = Kp = Km
B.	Kc = Kp/RT = Km . RT/P
C.	Kc = Kp . RT = Km . RT/p
D.	None of these
Answer» D. None of these

Discussion

107.	With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent
A.	Increases
B.	Decreases
C.	Remain same
D.	Either (A) or (B), depends on the system
Answer» C. Remain same

Discussion

108.	Laboratory determination of the diffusivity of vapor is done by __________ method.
A.	Wetted wall column
B.	Gilliland's
C.	Winkelmann's
D.	Wike's
Answer» D. Wike's

Discussion

109.	Raschig ring made of porcelain cannot be used for treating concentrated
A.	Hydrochloric acid
B.	Nitric acid
C.	Alkalis
D.	Sulphuric acid
Answer» D. Sulphuric acid

Discussion

110.	The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through nondiffusing gas 'B' is
A.	1
B.	∞
C.	0.5
D.	2
Answer» B. ∞

Discussion

111.	Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.)
A.	(1 + Ro) = Ro/Ri
B.	(1 - Ro) = Ro/Ri
C.	(1 + Ri) = Ro/Ri
D.	(1 - Ri) = Ro/Ri
Answer» B. (1 - Ro) = Ro/Ri

Discussion

112.	The cooling effect in a cooling tower cannot be increased by
A.	Increasing the air velocity over the wet surfaces
B.	Reducing the humidity of entering air
C.	Lowering the barometric pressure
D.	None of these
Answer» E.

Discussion

113.	The equipment used in the extraction of highly corrosive radioactive liquids is
A.	Pulse column
B.	Spray column
C.	Mixer settler
D.	Baffle tower
Answer» B. Spray column

Discussion

114.	The value of „L/mG’ ratio for economical absorption operation ranges from
A.	0.5 to 0.8
B.	0.8 to 1.2
C.	1.25 to 2.0
D.	2.5 to 3.5
Answer» D. 2.5 to 3.5

Discussion

115.	In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction xf = 0.2. The mixture splits into an extract phase E and a raffinate phase R containing A at xB = 0.5 and xR = 0.05 respectively. The total mass of the extract phase is (in Kg)
A.	6.89
B.	8.89
C.	10
D.	8.25
Answer» C. 10

Discussion

116.	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 hysteresis. In such cases, the desorption equilibrium pressure is __________ that obtained for adsorption.
A.	Lower than
B.	Higher than
C.	Same as
D.	Either same or higher than
Answer» B. Higher than

Discussion

117.	The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume ofquiescent liquid, in which „D’ is the diffusivity of solute, is
A.	D/a
B.	D/2a
C.	Proportional to √D
D.	Dependent on the Reynolds number
Answer» E.

Discussion

118.	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 column.
A.	5
B.	9
C.	12
D.	28
Answer» D. 28

Discussion

119.	In an absorption column, the flooding velocity for random packing is __________ that for stacked/regular packing.
A.	Greater than
B.	Smaller than
C.	Equal to
D.	Either (A), or (B); depends on the type of packing
Answer» C. Equal to

Discussion

120.	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 × 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:
A.	5.6 × 10-4
B.	8.5 × 10-4
C.	5.6 × 10-3
D.	8.5 × 10-3
Answer» C. 5.6 × 10-3

Discussion

121.	Cox chart, which is useful in the design of distillation column particularly for petroleumhydrocarbons, is a plot of (where, P = vapor pressure, T = temperature).
A.	log P vs. T
B.	log P vs. log T
C.	T vs. P
D.	P vs. log T
Answer» B. log P vs. log T

Discussion

122.	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.	Remain same
D.	Increases linearly
Answer» B. Decreases

Discussion

Explore topic-wise MCQs in Mass Transfer.

As the reflux ratio in a distillation column is increased from the minimum, the

In extraction, as the temperature increases, the area of heterogeneity (area covered by binodal 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 )

A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is:

With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent

Laboratory determination of the diffusivity of vapor is done by __________ method.

Raschig ring made of porcelain cannot be used for treating concentrated

The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through nondiffusing gas 'B' is

Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.)

The cooling effect in a cooling tower cannot be increased by

The equipment used in the extraction of highly corrosive radioactive liquids is

The value of „L/mG’ ratio for economical absorption operation ranges from

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 hysteresis. In such cases, the desorption equilibrium pressure is __________ that obtained for adsorption.

The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume ofquiescent liquid, in which „D’ is the diffusivity of solute, is

In an absorption column, the flooding velocity for random packing is __________ that for stacked/regular packing.

Cox chart, which is useful in the design of distillation column particularly for petroleumhydrocarbons, is a plot of (where, P = vapor pressure, T = temperature).

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.