The oxidation state of each oxygen in $KO_{2}$ is:

Question

Accepted Answer

To determine the oxidation state of each oxygen in potassium superoxide ($KO_2$), we need to consider the structure and composition of the compound.

1. **Explanation for Option 3 ($-1/2$):**

Potassium superoxide ($KO_2$) is a compound where potassium (K) is combined with the superoxide ion ($O_2^-$). In this compound, potassium (K) typically has an oxidation state of +1. The superoxide ion ($O_2^-$) consists of two oxygen atoms sharing a total charge of -1. Therefore, the oxidation state of each oxygen atom in the superoxide ion is calculated as follows:

- The total charge of the superoxide ion is -1.
   - There are two oxygen atoms in the superoxide ion.
   - To find the oxidation state of each oxygen atom, we divide the total charge by the number of oxygen atoms: 
     $$
     \text{Oxidation state of each oxygen} = \frac{-1}{2} = -\frac{1}{2}
     $$

Thus, the oxidation state of each oxygen in $KO_2$ is $-1/2$, which supports Option 3 as the correct answer.

2. **Explanation for why other options are incorrect:**

- **Option 1 (-2):** This oxidation state is typical for oxygen in most compounds, such as oxides (e.g., $H_2O$, $CO_2$). However, in the superoxide ion ($O_2^-$), the oxidation state of oxygen is not -2 because the total charge of the ion is -1, not -2.

- **Option 2 (-1):** This oxidation state is characteristic of the peroxide ion ($O_2^{2-}$), where each oxygen has an oxidation state of -1. In the case of the superoxide ion ($O_2^-$), the total charge is -1, which is shared between two oxygen atoms, resulting in an oxidation state of $-1/2$ for each oxygen.

- **Option 4 (0):** An oxidation state of 0 would imply that the oxygen atoms are in their elemental form (e.g., $O_2$ gas), where there is no net charge. In $KO_2$, the oxygen atoms are part of the superoxide ion, which carries a charge, so their oxidation state cannot be 0.

In conclusion, the correct oxidation state of each oxygen in $KO_2$ is $-1/2$, making Option 3 the correct choice.