The elementary reaction $(2$A$?$R$)$ takes place in a CSTR followed by a PFR $)=(0\mathrm{.}04$min$-1.$ The feed contains pure $)=1\mathrm{.}0(atm),T=298(K),U_0=(10\frac{L}{m}in.$ What is the required volume to reach an overall conversion of $70\%$ if the CSTR is $100$L$?$ The pressure is constant throughout the system.