$($b$)$ Show that, in the absence of chemical reaction in the liquid phase, the concentration pro$-$

file is linear.

$($c$)$ Show that the rate of leaching is given by

$N_{Az}=D_{AB}\frac{c_{A0}-c_A}{}$

$($d$)$ how would the profile change if there was a zeroth order reaction of $A(AB,r_A=k)$