Statement I : Pb⁺² is more stable than Pb⁺⁴
Statement II : Pb⁺² has stable half-filled configuration

Pb⁺² is more stable than Pd⁺⁴
Due to inert pair effect Pb⁺² is stable
Due to poor shielding effect by completely filled d-oritals of inner shell, the valency S-orbital e^-s(6s) are strongly attracted by nucleus .Hence S-orbital electron pair does not involve in bonding this is said to be inert pair effect
Pb⁺² oxidation state is more stable than pb⁺⁴

electronic configuration of Pb⁺² ---  [Xe]6S² 6P⁰

It is not half-filled configuration