(N/A) The elements of group-$16$ exhibit a variety of oxidation states. The stability of the $(-2)$ oxidation state decreases down the group. Polonium hardly shows the $(-2)$ oxidation state.
Since the electronegativity of oxygen is very high,it shows only a negative oxidation state of $(-2)$,except in the case of $OF_{2}$,where its oxidation state is $(+2)$.
The elements of group-$16$ other than oxygen also show $(+2), (+4),$ and $(+6)$ oxidation states,but $(+4)$ and $(+6)$ are the most common. Sulfur,selenium,and tellurium usually show the $(+4)$ oxidation state in their compounds with oxygen and the $(+6)$ oxidation state with fluorine (e.g.,$SF_{6}$).
The stability of the $(+6)$ oxidation state decreases down the group,while the stability of the $(+4)$ oxidation state increases due to the inert pair effect. Bonding in the $(+4)$ and $(+6)$ oxidation states is primarily covalent.