$\mathrm{H}_{3} \mathrm{O}^{+}+\mathrm{A}^{-} \rightleftharpoons \mathrm{H}_{2} \mathrm{O}+\mathrm{HA}$
$\mathrm{OH^-}+\mathrm{HA} \rightarrow \mathrm{H}_{2} \mathrm{O}+\mathrm{A}^{-}$
If acid is added, it reacts with $A^-$ to form undissociated $HA$. Similarly, if base/alkali is added, $OH^-$ combines with $HA$ to give $H_2O$ and Aand thus, maintains the acidity/alkalinity of buffer solution.
(નજીકના પૂર્ણાંકમાં રાઉન્ડ ઑફ કરો) $[$આપેલ $: \sqrt{2}=1.41]$