$A+Bhar{r}^{k_1}D,$ desired $r_D=2\mathrm{.}0C_A^{1\mathrm{.}1}{C}_B^{0\mathrm{.}3},mo\frac{l}{L}*min$

$A+Bhar{r}^{k_2}R,$ undesired $r_U=1\mathrm{.}0C_A^{0\mathrm{.}5}{C}_B^{1\mathrm{.}9},mo\frac{l}{L}*min$

For $90\%$ conversion of A find the concentration of $R$ in the product stream. Equal volumetric flow rate of A and of B streams are fed to the reactor, and each stream has a concentration of $10mo\frac{l}{L}$ of reactant.

The flow in reactor follows

a$).(3$ pts$)$ Plug flow reactor

b$).(2$ pt$)$ CSTR

c$).(1$ pt$)$ Recommend a reactor combination to answer. No calculation is needed in part c$.$