Only one litre buffer solution was prepared by adding \(0.10\) mol each of \({\mathrm{NH}}_{3}\) and \({\mathrm{NH}}_{4}…

Only one litre buffer solution was prepared by adding \(0.10\) mol each of \({\mathrm{NH}}_{3}\) and \({\mathrm{NH}}_{4}\mathrm{Cl}\) in deionised water. The change in pH on addition of \(0.05\) mol of \(\mathrm{HCl}\) to the above solution is ____ \(\times {10}^{-2}\), (Nearest integer) (Given : \({\mathrm{pK}}_{\mathrm{b}}\)of \({\mathrm{NH}}_{3}=4.745\) and \({\log }_{10}3=0.477\) )