Question

In metal halides in higher oxidation state of the metal is more covalent than the one in lowest oxidation state ($PbC{l}_4$ is more covalent than $PbC{l}_2$)

Answer 1

The halides in higher oxidation state posses high charge and are smaller in size as compared to the lower oxidation state halides.
Thus, in higher oxidation halides the charge/radius ratio is higher which contribute to the increase in polarisation and consequently these are more covalent.