The reaction,${\mathrm{A}}_{\left(\mathrm{g}\right)}+2{\mathrm{B}}_{\left(\mathrm{g}\right)}\to {\mathrm{C}}_{\left(\mathrm{g}\right)}+{\mathrm{D}}_{\left(\mathrm{g}\right)}$ is an elementary process . In an experiment, the initial partial pressure of A and B are ${\mathrm{P}}_{\mathrm{A}}=0.60 \mathrm{and} {\mathrm{P}}_{\mathrm{B}}=0.80 \mathrm{atm}. \mathrm{When} {\mathrm{P}}_{\mathrm{C}}=0.2 \mathrm{atm}$the rate of reaction relative to the initial rate is