find the internal efficiency factor $\backslash$eta as a function of Thiele number for a zero$-$order reversible reaction of zero order A $-->$ B in an isothermal porous catalytic plate of thickness L exposed to the reactants from one side only. hint: the concentration of A may be zero at some distance zm from the surface of the plate, which should be determined and compared with the thickness L$.$ If zm$>=$L$,$ the concentration of A is non$-$zero at any distance from the surface. If zm$=$ zm