Question

pb+4 act as oxidizing agent but Sn+2 act as reducing agent?

Answer 1

It is due to inert pair effect.

Pb+4 is less stable so it wants to become Pb+2 and in order to become Pb+2 it has to gain +2 electrons and hence it will act as oxidising agent.

And Sn+4 is more stable as compared to Sn+2
so, Sn+2 wants to become Sn+4 and therefore it has to lose 2 electron and hence it acts as reducing agent.