Under the same conditions
A.1 m3 of dry air is lighter than 1 m3 of humid air
B.1 m3 of humid air is lighter than 1 m3 of dry air
C.both 1 m3 of dry air and 1 m3 of humid air have the same weight
Category: Mass Transfer Mcqs
The binary diffusivity in gases at atmospheric conditions is of the order of
A.10-1 cm2/sec
B.10-5 cm2/sec
C.105 cm2/sec
D.10-7 cm2/sec
Entrainment in a distillation column
A.is defined as the liquid carried with the vapour from one tray to the tray above
B.is detected by decrease in Murphree plate efficiency
C.may be detrimental since it can carry non-volatile constituents upward
D.all of these answers
The Knudsen diffusivity is proportional to where T = absolute temperature
A.T
B.T 3/2
C.T 1/2
D.T2
Entrainer used in azeotropic distillation of binary mixture
A.forms no azeotrope with the original substances
B.forms a minimum boiling azeotrope with one or both of the feed components
C.should be of very high viscosity to provide high tray efficiencies
D.should have very high latent heat of vaporization
In a cooling tower makeup fresh water must be added to replace losses from
A.entrainment
B.evaporation losses
C.blowdown
D.all of the above
Which of the following is more accurate to determine the number of theoretical stages required for the separation of nonideal binary systems by distillation?
A.McCabe ? Thiele method
B.Ponchon ? Savarit method
C.Both McCabe ? Thiele and Ponchon ? Savarit methods are equally good.
If y* = x the relative volatility ? for a binary system is always
A.zero
B.one
C.infinity
D.one except at x = 0 or 1
The ratio of the actual equilibrium partial pressure of a component to the ideal value is called
A.activity coefficient
B.turbdown ratio
C.relative volatility
D.fugacity
At minimum reflux ratio the operating cost of a distillation column is
A.maximum possible
B.optimum
C.minimum
D.infinite
