m tr Flashcards
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
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
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.
C
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
C
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
B
Total reflux in a distillation operation requires minimum
A. reboiler load.
B. number of plates
C. condenser load
D. all (a), (b) and (c)
B
As the reflux ratio in a distillation coloumn 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.
C
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).
C
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
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).
D
__________ columns are used for liquid dispersion in a
continuous gas phase.
A. Packed
B. Pulse
C. Bubble cap
D. Sieve plate
A
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
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
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)
D
Which is the controlling factor for a drum drier?
A. Diffusion
B. Heat transfer
C. Both (a) and (b)
D. Neither (a) nor (b)
B
The difference of wet bulb temperature and adiabatic saturation
temperature of unsaturated mix. of any system is
A. +ve
B. -ve
C. zero
D. none of these
A
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
B
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.
C
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
C
Stefan’s law describes the mass transfer by
A. diffusion
B. bulk flow
C. both ‘a’ & ‘b’
D. neither ‘a’ nor ‘b’
C
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.
B
Relative humidity is the ratio of the
A. partial pressure of the vapour to the vapour pressure
of the liquid at room temperature.
B. partial pressure of the vapour to the vapour pressure
of the liquid at gas temperature.
C. actual humidity to saturation humidity.
D. none of these
B
In batch distillation with constant reflux, overhead product
composition __________ with time.
A. increases
B. decreases
C. does not vary
D. may increase on decrease, depends on the system.
B
constant reflux=decrease
Psychrometry deals with the properties of gas-vapor mixture.
Humidity can be determined by the measurement of the
__________ of a fibre.
A. electrical resistance
B. thermal conductivity
C. strength
D. none of these.
A