Question

InCl undergoes disproportionate reaction while TlCl does not. Why?

Answer 1

InCl undergoes disproportionation in water as follows:
$3InCl\to 2In+I{n}^{3+}+3C{l}^{-}$
On moving down the group of p block elements, stability of higher oxidation state decreases.Therefore, Tl has less tendency to form Tl³⁺ ion and thus it doesnot disproportionate.