$($b$)$ For a parallel decomposition of A$,$ where $R$ is the desired product,

$AR,r_R=1$

$AS,r_S=2C_A$

$AT,r_T=C_A^2$

with $C_{A0}=4,$ what is the maximum $C_R$ we may expect in isothermal operations

$($i$)$ in a mixed flow reactor

$(5)$

$($ii$)$ in a plug flow reactor.