Which column is most likely to form a -2 anion?

The Oxygen group, also known as Group 16 of the periodic table, is most likely to form a -2 anion. This is primarily due to the electronic configuration and the tendency of oxygen and its group members to gain electrons in a chemical reaction.

Elements in this group have six valence electrons and require two additional electrons to achieve a stable octet configuration. Therefore, when oxygen and other elements in this group react, they tend to gain two electrons, resulting in the formation of a -2 anion, commonly referred to as an oxide ion (O²⁻). This behavior is characteristic of nonmetals, particularly oxygen, sulfur, and selenium, which commonly exhibit this -2 oxidation state in compounds.

In contrast, the other groups listed do not favor the formation of -2 anions. The Carbon group typically forms covalent bonds and can either lose or share electrons rather than gaining two to form anions. The Nitrogen group generally forms -3 anions or covalently bonds, while the Halogens are known for forming -1 anions due to their seven valence electrons and preference for gaining just one additional electron to complete their octets.