An object with an area of $2$cm$2$ is moving to the right in the $+$z direction with a bulk velocity of

$4$cm$/$s$.$ In the volume at steady state there are $5$ moles of A $($M$=3$g$/$mol$),3$ moles of B $($M$=$

$2$g$/$mol$).$ Molecule A diffuses in $+$z direction with a diffusion rate of $3$ mol$/$s and molecule B

diffuses in the opposite direction with a diffusion rate of $2$mol$/$s$.$ Calculate:

a$)$ Molar average velocity of each component $()$

b$)$ Mass average velocity of each component $()$