b$)$ Pure gas $A$ is diffusing from a point $1$ at a partial pressure of $1$

atm. to a point $2$ at a distance $1\mathrm{.}0mm$ away. At point $2$ it

undergoes instantaneous chemical reaction at the catalytic surface

as $A3B$

Gas $B$ diffusing back at the steady state. The total pressure is $1$

atm. and temperature is $27C.$ The molecular diffusivity, DAB$=$

$1\mathrm{.}510-5m\frac{2}{s}.$ Calculate molar flux of $A(kgmo\frac{l}{m}2s)$ at steady

state