The following basic reaction is carried out in a liquid MFR$.1$ mol$/$m$3$ of pure reactant A flows into the reactor at a rate of $2$m$3/$min$.$ If one reactor with volume $10$ m$3$ is used and two reactors with volume $5$ m$3$ are used in series, find the concentration of R that can be obtained at the outlet of the reactor in each case, compare the results with each other and explain why.