\(25\% ;\,\,\,pH = {p^{{K_a}}} + \log \frac{{Salt}}{{Acid}}\,\,\,pH = {p^{{K_a}}} + \log \frac{{25}}{{75}}\)
\(50\% \,pH = {p^{{K_a}}} + \log \frac{{50}}{{50}}\,\,\,\,75\% \,pH = {p^{{K_a}}} + \log \frac{{75}}{{25}}\)
$2N{H_3}\, \rightleftharpoons \,N{H_4}^ + \, + \,N{H_2}^ - $
(આપેલ : $K _{ b }\left( NH _4 OH \right)=1 \times 10^{-5}, \log 2=0.30, \log 3=0.48, \log 5=0.69, \log 7=0.84, \log 11=$ $1.04)$
$[$પાણીનો આયનીય ગુણાકાર $ = 1 \times {10^{ - 14}}]$