Inert pair effect is predominant in Pb.
Explanation
The inert-pair effect is the tendency of the two electrons in the outermost atomic s-orbital to remain unshared in compounds of post-transition metals. In lead (Pb) inert pair effect is most prominent because as we move down the group from carbon to lead the tendency of non-participation inner ns electrons in chemical bonding increases due to the large size of atoms.
So Pb is having more tendency of showing an inert pair effect.
