The pH of an aqueous solution containing 1 M benzoic acid ( pK_a =4.20) and 1 M sodium benzoate is 4.5. The volume of benzoic acid solution in 300 mL…

The pH of an aqueous solution containing $\displaystyle 1$ M benzoic acid $\displaystyle \left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$ and $\displaystyle 1$ M sodium benzoate is $\displaystyle 4.5$ . The volume of benzoic acid solution in $\displaystyle 300$ mL of this buffer solution is $\displaystyle \_\_\_\_$ mL . (given $\displaystyle : \log 2=0.3$ )