\( 20 \,\mathrm{mL} \) of \( 0.1 \,\mathrm{M} \; \mathrm{NH_4OH} \) is mixed with \( 40 \,\mathrm{mL} \) of \( 0.05 \,\mathrm{M} \; \mathrm{HCl} \). The pH of the mixture is nearest to :
(Given : \( K_b(\mathrm{NH_4OH}) = 1 \times 10^{-5} \), \( \log 2 = 0.30 \), \( \log 3 = 0.48 \), \( \log 5 = 0.69 \), \( \log 7 = 0.84 \), \( \log 11 = 1.04 \))
