Which of the following statements about oxidation states is incorrect?

The statement regarding the total oxidation number being always equal to 1 is incorrect because the total oxidation number of a compound is determined by the sum of the oxidation states of all the atoms within that compound. This sum can vary widely depending on the specific elements and their oxidation states involved. For neutral compounds, the total oxidation number is 0, while for polyatomic ions, it equates to the charge of that ion. Therefore, suggesting that it is always equal to 1 does not hold true across all compounds and ions.

In contrast, the other statements about oxidation states are accurate. The oxidation number of oxygen is generally -2, with some exceptions such as in peroxides or superoxides. Fluorine is recognized as having an oxidation number of -1 due to its high electronegativity and its tendency to attract electrons. Additionally, natural elemental forms of an element, such as O₂ or Fe, exhibit an oxidation number of 0, as their atoms are in their standard states and are not combined with any other elements. Understanding these principles is crucial for analyzing the oxidation states in various chemical contexts.