Equilibrium: JEE Main 2025 Chemistry question

One litre buffer solution was prepared by adding 0.10 mol each of $\mathrm{NH_3}$ and $\mathrm{NH_4Cl}$ in deionised water. The change in pH on addition of 0.05 mol of HCl to the above solution is ______ $\times10^{-2}$. (Nearest integer) Given : $\mathrm{p}K_b$ of $\mathrm{NH_3}=4.745$ and $\log_{10}3=0.477$