Q$2.$ A gas $($A$)$ diffuses at steady$-$state through a tube containing another inert gas $($B$).$ At point $1$ the partial pressure of $A$ is $P_{A1}=45$kPa and at point $2$ is $P_{A2}=10$kPa. The length of the tube is $4cm.$ The total pressure is $101\mathrm{.}32$kPa and the temperature is $273K.$ At this pressure and temperature the value of diffusivity is $6,55{10}^{-5}.$

Calculate the flux of $A$ at steady$-$state for equimolar counter diffusion $R=8314$