Account for the following observation:

${\mathrm{PbO}}_2$ is a stronger oxidising agent than ${\mathrm{SnO}}_2$

Account for the following observation:

The $+1$ oxidation state of thallium is more stable than its $+3$ state.

Identify that compound in the following pair which has group $13$ element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.

${\mathrm{TlCl}}_3, \mathrm{TlCl}$

Identify that compound in the following pair which has group $13$ element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.

${\mathrm{AlCl}}_3, \mathrm{AlCl}$

Identify that compound in the following pair which has group $13$ element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.

${\mathrm{InCl}}_3, \mathrm{InCl}$