Ionic Equilibrum

A buffer solution has equal volumes of \(0.1 \mathrm{~M} \mathrm{~NH}_4 \mathrm{OH}\) and \(0.01 \mathrm{~M} \mathrm{~NH}_4 \mathrm{Cl}\). The \(\mathrm{pK}_b\) of the base is 5. The \(\mathrm{pH}\) is