Unlike `In^(+),Tl^(+)` does not undergo disproportiona- tion reaction-Explain.

Explanation

Both In and Tl can exhibit oxidation states of + 1 and +3 . However, because of prominent inert pair effect in Tl, the + 1 oxidation state of Tl is more stable than its +3 oxidation state while +3 oxidation state of In is more stable than its + 1 oxidation state. As a consequence, in aqueous solution, the less stable In+ undergoes disproportionation reaction to form more stable `In^(3+)" but " Tl^(+)` being more stable, does not undergo disproportionation reaction.
`3overset(+1)(In)(aq) overset("Disproportionation")to 2overset0(In)(s) + overset(+3)(In)(aq)`