.4. Reactant A(AR,CA0=26mol/m3) passes in steady flow through four equal-size mixed flow reactors in series (total=2min). When steady state is achieved the concentration of A is found to be 11,5,2,1mol/m3 in the four units. For this reaction, what must be plug so as to reduce CA from CA0=26 to CAf=1mol/m3