A gas phase reaction is to be carried out in an isothermal batch reactor \[ 2 \mathrm{~A} \longrightarrow \mathrm{~B} \] The reaction is second order : \( \mathrm{r}_{\mathrm{A}}=\mathrm{kC}_{\mathrm{A}}^{2} \). A conversion of \( 90 \% \) must be achieved. Calculate the ratio of the residence time of a constant volume reactor to residence time of a constant pressure reactor. Initially both reactors are of the same volume and at the same pressure, and no product \( B \) is present. Why is the ratio of residence times greater than, or less than unity ? (Both reactors operate at the same temperature and mixture behaves as a perfect gas)