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 $PbCl$)

Answer 1

Generally $Pb$ is a soft metal and forms tetrachlorides easily in the form of $MC{l_4}$. Before that we know about the covalent character and inert pair effect.

Complete step by step answer: Let us understand the covalent character of ionic bonds: when a cation approaches an anion, the electron cloud of the anion is attracted to the cation and hence gets distorted. The effect is known as polarisation of ions. The greater is the polarisation produced, the more is the neutralisation of the charge, and hence the covalent character decreases.
Inert pair effect: Inert pair effect is defined as the reluctance of the s-electrons of the valence hell to take part in bonding. This happens due to poor shielding of the ns electrons.
The charge on $Pb$ in $PbC{l_4}$ is +4 and $PbCl$ is +1 . According to Fajan’s rule, the charge on the cation is greater which has more ability to give a better covalent character to the compound by polarising the bonding electrons.$PbCl$ has a greater change and hence is covalent.

Additional information: With the help of Fajan’s we can calculate or find the order of the covalent character of the compounds. Fajan’s rule is based on the size of the cation. The melting point of the compound can be calculated by the force of attraction between the ions.

Note: All halides are covalent when they bond to each other, and all halides are naturally diatomic. Halides can only be ionic when bonded to an alkaline metal, making them salts. Salts are always ionic.