Answer:
The Inert Pair effect renders Pb(II) as the more stable oxidation state of lead
Explanation:
SnBr4 + PbBr2 ---> SnBr2 + PbBr4
SnBr2 + PbBr4 ---->
The Inert pair effect is mostly observed between group 15-17 in the periodic table. It leads to stability of the lower oxidation state of an element.
The reason for the Inert pair effect is that the s electrons become Inert due to poor shielding of the d and f-electrons. The Inert pair effect is a tendency of the s electrons not to participate in bonding (remain an Inert pair).
Owing to the Inert pair effect, Pb II is more stable than Pb IV