Explain inert pair effect with example.

Explanation

Both `"In"^+` and `TI^+` are Group 13 elements. Elements of group 13 have three electrons in their valence shell `(ns^2 np^1)` and thus exhibit an oxidation state of +3. In addition to this they also exhibit an oxidation state of +1, which becomes more and more stable as we move down the group. This is because the pair of electrons of the s-orbital in the valence shell remain paired and do not participate in bonding. As such +1 oxidation state of thallium is more stable than +3 oxidation state and hence `Tl^+` is stable with respect to disproportionation reaction.