Question

In III A group ,Tl (Thalium) shows stable +1 oxidation state, while boron shows stable +3 oxidation state. It is due to

Answer 1

For TL, after the removal of one electron from p-orbital , the remaining 6s2 electrons behave like stable noble gas and do not take part in compound formation.

This reluctance of the s-electron pair to take part in chemical combination is called inert pair effect.

So +1 oxidation state more stable for Tl

Due to the absence of inert pair effect B does not show +1 oxidation state.

Hence b is the correct answer.