JEE Main 2023 Chemistry question on Solutions

Solid Lead nitrate is dissolved in 1 litre of water. The solution was found to boil at 100.15° C. When 0.2 mol of NaCl is added to the resulting solution, it was observed that the solution froze at -0.8° C. The solubility product of $\text{PbCl}_2$ formed is _________ $\times 10^{-x}$ at 298 K. (Nearest integer)

Given : $K_b = 0.5$ K kg mol$^{-1}$ and $K_f = 1.8$ K kg mol$^{-1}$. Assume molality to be equal to molarity in all cases.