What is the oxidation state of oxygen in most compounds?

The oxidation state of oxygen in most compounds is commonly -2. This occurs because oxygen typically forms two bonds to achieve a stable electron configuration, aligning with its position in Group 16 of the periodic table, where it has six valence electrons. By gaining two electrons, oxygen can reach a complete octet, resulting in a -2 oxidation state.

This -2 oxidation state is observed in a wide variety of oxygen-containing compounds, such as water (H2O), carbon dioxide (CO2), and many metal oxides (like magnesium oxide, MgO). There are exceptions, such as in peroxides (where it has an oxidation state of -1) and superoxides (where it can be -1/2), but these are less common.

In this context, while the other options suggest possible oxidation states of oxygen, they are not typically applicable. The neutral state (0) and +1 oxidation state are not seen under normal conditions, and while oxidation states of -1 exist in specific compounds, they do not apply to the majority of oxygen compounds. Therefore, the -2 state is the most prevalent and widely recognized oxidation state for oxygen in chemical compounds.