Based on acetic acid $\left(K_{\mathrm{a}}^{\circ }=1.8\times {10}^{-5}\right)$ solution,

If the solution obtained in Q.99 is diluted 10 times, it pH becomes

$\begin{array}{l}M\left({\mathrm{CH}}_3\mathrm{COONa}\right)=82\mathrm{g}{\mathrm{mol}}^{-1}\\ n\left({\mathrm{CII}}_3{\mathrm{COONa}}^{-}m/M-0.82\mathrm{g}/82\mathrm{g}{\mathrm{mol}}^{-1}-0.01\mathrm{mol}\right.\\ c\left({\mathrm{CH}}_3\mathrm{COONa}\right)=n/V=0.01\mathrm{mol}/0.1\mathrm{L}=0.1\mathrm{M}\\ \mathrm{pH}=\mathrm{p}{K}_{\mathrm{a}}+\log \left[\mathrm{salt}\right]/\left[\text{ acid }\right]=-\log \left(1.8\times {10}^{-5}\right)+\log (0.1/0.1)=4.75\end{array}$

from the given condition the solution is diluted 10 times. then 

The pH of buffer solution does not change on dilution.