Q-Give reason to explain the stability of +3 oxidation state of Bi as compared to +5.

Dear student,Actually, from top to bottom down the group, the d and f -orbitals have poor sheilding effects in theses elements as a result of which the effective nuclear charge increases for ns electrons and they feel attraction towards the nucleus and become inert towards the chemical reaction which is known as the inert pair effect. Due, to this inert pair effect, the +5 oxidation state does not become stable.Regards.