Question

in most compounds, the oxidation number of oxygen is ______.
-1
-2

Explanation:

In most chemical compounds, oxygen typically has an oxidation number of -2. This is a fundamental rule in oxidation - number determination. For example, in compounds like \(H_2O\) (water), the oxidation number of oxygen is -2 (while hydrogen has an oxidation number of +1, and \(2\times( + 1)+(-2)=0\) which satisfies the rule that the sum of oxidation numbers in a neutral compound is zero). The oxidation number of -1 for oxygen is more common in peroxides (e.g., \(H_2O_2\), hydrogen peroxide), which are not the "most compounds" case here.

Answer:

-2 (the option corresponding to -2, which would be the second option in the given choices: the option with -2)