The pH of a solution obtained by mixing 5 mL of 0.1 M NH_4 OH solution with 250 mL of 0.1 M NH_4 Cl solution is ____ × 10^-2.(Nearest integer) Given:…

The pH of a solution obtained by mixing $\displaystyle 5$ mL of $\displaystyle 0.1 \mathrm{M} \mathrm{NH}_4 \mathrm{OH}$ solution with $\displaystyle 250$ mL of $\displaystyle 0.1 \mathrm{M} \mathrm{NH}_4 \mathrm{Cl}$ solution is $\displaystyle \_\_\_\_$ $\displaystyle \times 10^{-2}$.(Nearest integer) Given: $\displaystyle \mathrm{pK}_{\mathrm{b}}\left(\mathrm{NH}_4 \mathrm{OH}\right)=4.74$ $$\begin{aligned} & \log 2=0.30 \\ & \log 3=0.48 \\ & \log 5=0.70 \end{aligned} $$