Ionic Equilibrium

\(20 \mathrm{~mL}\) of \(0.1\, \mathrm{M} \,\mathrm{NH}_{4} \mathrm{OH}\) is mixed with \(40 \mathrm{~mL}\) of \(0.05 \mathrm{M} \mathrm{HCl}\). The \(\mathrm{pH}\) of the mixture is nearest to :

(Given : \(\mathrm{K}_{\mathrm{b}}\left(\mathrm{NH}_{4} \mathrm{OH}\right)=1 \times 10^{-5}, \log 2=0.30, \log 3=0.48, \log 5=0.69, \log 7=0.84, \log 11= 1.04)\)