Please reference this text Separation Process Principles$3$rd edition

Chemical and Biochemical Operations

Choose the correct multiple choice explain why

About mass transfer:

D$.$ In stagnant media, molecular diffusion is the only mass transfer mechanism.

C$.$ Molecular diffusion is the result of the collective movement of individual molecules

under a concentration gradient.

B$.$ Molecular diffusion flux tends to enhance concentration gradients.

A$.$ In turbulent flow, eddy diffusion due to macroscopic fluid motion occurs, which is

much faster than molecular diffusion.

For binary diffusion:

D$.$ DAB$=$DBA

C$.$ JA$=$JB

B$.$ xA$=$xB

A$.$ vM$=($JA$+$JB$)/$c

About diffusivity:

DA$.$ Diffusion in gas is much faster than that in liquid and solid.

CB$.$ Diffusivity in gas increases with temperature and pressure.

BC$.$ The diffusivity of a species in liquids decreases with liquid viscosity and species size.

AD$.$ Diffusivity is strongly dependent on the composition and chemistry of the mixture.

About turbulent flow,

DA$.$ It$$s less common in the chemical industry.

CB$.$ There is no streamline except near the wall.

BC$.$ Mass transfer in the normal direction occurs due to only eddy diffusion.

AD$.$ Eddy diffusion leads to faster mass$/$heat transfer, resulting in smaller equipment.