Acetone $($A$)$ is evaporating from a stagnant layer of benzene $($B$)$ at $25\backslash$deg C$.$ The

concentration of acetone at the interface $($z $=0)$ is $,$s $=0\mathrm{.}1$ kg$/$m$^3,$ and the bulk

concentration of acetone in the benzene $($far from the interface$)$ is $,\backslash$infty $=0\mathrm{.}001$ kg$/$m$^3.$

The diffusion coefficient of acetone in benzene at $25\backslash$deg C is $.).=1\mathrm{.}2$ x $10^-9$ m$^2/$s$.$

According to Fick's Law of Diffusion, express the mass flux $(.)$ of acetone in terms of

concentration $(.)$ and diffusion coefficient $(.$