Three pairs of compounds are given below. Identify the compound in each pair which has the group $13$ element in a more stable oxidation state. Give reasons for your choice and state the nature of bonding. $(A)$ $TlCl_3, TlCl$ $(B)$ $AlCl_3, AlCl$ $(C)$ $InCl_3, InCl$

(A-D) $TlCl$ is more stable than $TlCl_3$ because,moving down the group,the lower oxidation state $(+1)$ becomes more stable due to the inert pair effect. $TlCl$ is ionic,while $TlCl_3$ is covalent.
$(B)$ $AlCl_3$ is more stable than $AlCl$ because $Al$ does not exhibit the inert pair effect. $AlCl_3$ is a covalent compound that acts as a Lewis acid.
$(C)$ $InCl$ is more stable than $InCl_3$ due to the inert pair effect,which makes the $+1$ oxidation state more stable for heavier elements. $In$ exhibits both $+3$ and $+1$ oxidation states. The reaction is: $3 InCl_{(aq)} \rightarrow 2 In_{(s)} + In_{(aq)}^{3+} + 3 Cl_{(aq)}^{-}$