IndiaBIX Chemical Engineering: Mass Transfer Section 1 Flashcards
1
Q
- Mass transfer rate between two fluid phases does not necessarily depend on the __________ of the two phases.
A. chemical properties
B. physical properties
C. degree of turbulence
D. interfacial area
A
chemical properties
2
Q
- In a solution containing 0.30 Kg mole of solute and 600 kg of solvent, the molality is
A. 0.50
B. 0.60
C. 2
D. 1
A
0.5
3
Q
- Fenske equation determines the
A. maximum number of ideal plates.
B. height of the distillation column.
C. minimum number of theoretical plates.
D. optimum reflux ratio.
A
minimum number of theoretical plates.
4
Q
- The term “cooling range” in a cooling tower refers to the difference in the temperature of
A. cold water leaving the tower and the wet bulb temperature of the surrounding air.
B. hot water entering the tower and the wet bulb temperature of the surrounding air.
C. hot water entering the tower and the cooled water leaving the tower.
D. none of these
A
hot water entering the tower and the cooled water leaving the tower.
5
Q
- Which of the following is the most suitable for extraction in a system having very low density difference ?
A. Mixer-settler extractor
B. Centrifugal extractor
C. Pulsed extractor
D. Packed extraction tower
A
Centrifugal extractor
6
Q
- Total reflux in a distillation operation requires minimum
A. reboiler load
B. number of plates
C. condenser load
D. all (a), (b) and (c)
A
number of plates
7
Q
- The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by
A. raising the temperature.
B. lowering the total pressure.
C. both (a) and (b).
D. neither (a) nor (b).
A
both (a) and (b).
8
Q
- The difference of wet bulb temperature and adiabatic saturation temperature of unsaturated mixture of any system is
A. +ve
B. -ve
C. zero
D. none of these
A
+ve
9
Q
- Fenske’s equation for determining the minimum number of theoretical stages in distillation column holds good, when the
A. relative volatility is reasonably constant.
B. mixture (to be separated) shows negative deviation from ideality.
C. mixture (to be separated) shows positive deviation from ideality.
D. multicomponent distillation is involved.
A
relative volatility is reasonably constant.
10
Q
- When the temperature and humidity of air is low, we usually use __________ draft cooling tower.
A. natural
B. forced
C. induced
D. none of these
A
Natural
11
Q
- Pick out the correct statement.
A. In case of liquid-liquid extraction, no separation is possible, if the selectivity of the solvent used is unity.
B. With increase in temperature, the selectivity of the solvent used in solvent extraction decreases.
C. The selectivity of solvent used in solvent extraction is unity at the plait point.
D. all (a), (b) and (c).
A
all (a), (b) and (c).
12
Q
- __________ columns are used for liquid dispersion in a continuous gas phase.
A. Packed
B. Pulse
C. Bubble cap
D. Sieve plate
A
Packed
13
Q
- Overall efficiency of the distillation column is
A. the ratio of number of ideal plates to actual plates.
B. the ratio of number of actual plates to ideal plates.
C. same as the Murphree efficiency.
D. always more than the point efficiency.
A
the ratio of number of ideal plates to actual plates.
14
Q
- On addition of solute in the solvent, the __________ of the solution decreases.
A. boiling point
B. freezing point
C. vapour pressure
D. both (b) and (c)
A
both (b) and (c)
15
Q
- Which is the controlling factor for a drum drier?
A. Diffusion
B. Heat transfer
C. Both (a) and (b)
D. Neither (a) nor (b)
A
Heat transfer
16
Q
- Drying operation under vacuum is carried out to
A. dry those materials which have very high unbound mositure content.
B. reduce drying temperature.
C. increase drying temperature.
D. dry materials having high bound moisture content.
A
reduce drying temperature.
17
Q
- Air initially at 101. 3 kPa and 40°C and with a relative humidity of 50%, is cooled at constant pressure to 30°C. The cooled air has a
A. higher dew point.
B. higher absolute (specific) humidity.
C. higher relative humidity
D. higher wet bulb temperature.
A
higher relative humidity
18
Q
- Separation of two or more components of a liquid solution can not be achieved by
A. fractional crystallisation
B. liquid extraction
C. absorption
D. evaporation
A
absorption
19
Q
- Stefan’s law describes the mass transfer by
A. diffusion
B. bulk flow
C. both ‘a’ & ‘b’
D. neither ‘a’ nor ‘b’
A
both ‘a’ & ‘b’
20
Q
- At minimum reflux ratio for a given separation
A. number of plates is zero.
B. number of plates is infinity.
C. minimum number of the theoretical plates is required.
D. separation is most efficient.
A
number of plates is infinity.