+ 2 oxidation state of lead is more stable than + 4, because of

IV A group elementsCommon oxidation state is : "+4"C shows :- +4 -4Si:- +4 [Stable]Ge, Sn;-  +2,+1,+4(stable)Pb:-    +2, +4(stable)→ For Ge, Sn +4 is stable oxidation state hence in +2 oxidation state they acts as reducing agents→ Where as for Pb +2 oxidation state is state [due to inert pair effect] hence in +4 oxidation state Pb acts as oxidising agent→ Higher oxidation state is due to involvement of ns and np electroni.e., ns2 np2  →  +4Lower oxidation state is due to involvement of only np electroni.e., ns2 np(2) ⇒ +2Higher oxidation stable stability dececreases from top to bottom Lower oxidation stability increases from top to bottomGe+2 < Sn+2 < Pb+2 Stability order