Dear Aspirant,

The elements of group 15 generally exhibit -3,+3 and +5 oxidation states.The tendency to exhibit -3 oxidation state decrease as we move down the group due to an increase in the size of the atom and metallic character .Group 15 elements consists of nitrogen,phosphorus,arsenic,antimony and bismuth.Bismuth hardly forms the any component in oxidation state of -3.In fact, the stability of the +5 state also decreases as we move down the group.BiF5  is the only well-characterized Bi(V) compound.Due to the inert pair effect , the stability of +5 state decrease and +3 state increase as we down the group in the periodic table.