The diffusivity has the same dimensions as
A.absolute viscosity
B.kinematic viscosity
C.density
D.concentration
Category: Mass Transfer Mcqs
Peclet number (NPe) for mass transfer is defined as
A.NRe/NSc
B.NReNSc
C.NSc/NRe
D.NShNSc
The partial pressure distribution of both components of a non-reacting binary mixture of ideal gases is non-linear
A.in the case of steady-state equimolal counter-diffusion
B.in the case of steady-state unimolal unidirectional diffusion
C.both in the case of steady-state equimolal counter-diffusion and steady-state unimolal unidirectional diffusion
In a distillation operation the heat removed in condenser
A.remains unaffected with change in reflux ratio
B.increases with increase in reflux ration
C.decreases with increase in reflux ration
D.and the heat required in reboiler decrease with increase in reflux ratio
To separate a binary mixture the relative volatility should be
A.equal to one
B.less than one
C.greater than one
D.greater than zero
The binary diffusivity in liquids is of the order of
A.10-5 cm2/sec
B.10-5 m2/sec
C.10-5 mm2/sec
D.10-5 ft2/sec
Lewis number plays an important role in problems of
A.heat transfer only
B.mass transfer only
C.simultaneous heat and mass transfer
D.momentum transfer only
The dew point of an unsaturated mixture of vapour and gas does not depend on
A.the temperature of the mixture
B.the total pressure of the mixture
C.the composition of the mixture
D.all of the above
A two-phase is said to be in physical equilibrium if
A.the temperature of the vapour phase is equal to the temperature of the liquid phase
B.the total pressure throughout the vapour phase is equal to the total pressure throughout the liquid phase
C.the tendency of each phase is exactly equal to its tendency to escape from the vapour phase to the liquid phase
D.all of the above
The lewis number of a mixture is one when mass diffusivity is equal to
A.momentum diffusivity
B.thermal diffusivity
C.thermal conductivity
D.1/thermal diffusivity
