long with a radius of $0$ of $He(A)$ and $N_2(B)$ at $298K$ is diffusing through an open capillary $32mm$

$0\mathrm{.}687{10}^{-4}\frac{m^2}{s},=0\mathrm{.}32m)$

a$)$ Calculate the Knudsen diffusivity of $He(A).$

b$)$ Predict the flux $N_A$ for $x_{A1}=0\mathrm{.}70$ and $x_{A2}=0\mathrm{.}30.$ Assume a steady state.