A slab $15mm$ thick was immersed in flowing pure water $($B$).$ The slab has a uniform concentration of material $($A$)$ of $1\mathrm{.}0$kgmo$\frac{l}{m^3}.$ Neglecting the surface resistance, calculate the concentration of $($A$)$ after $26$ hours for the following cases:

$2.$ At $3\mathrm{.}0mm$ away from the center and the distribution coefficient $(K)$ is $1$

$3.$ At $4\mathrm{.}5mm$ away from the center and the distribution coefficient $(K)$ is $1$

$4.$ At $6mm$ away from the center and the distribution coefficient $(K)$ is $1$

$5.$ Plot the concentration as a function of position $($concentration profile in the slab$).$

Given data

$D_{AB}=6{10}^{-10}\frac{m^2}{s}$