Oxidation number of oxygen in `O_(2)^(2-)` ion is

Options

A. `-2`
B. `+1`
C. `-1`
D. `+2`

Answer

To determine the oxidation number of oxygen in the \( O_2^{2-} \) ion, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ion and its Charge**: We are given the ion \( O_2^{2-} \). The overall charge of this ion is -2.

2. **Assume the Oxidation State**: Let the oxidation state of each oxygen atom be \( x \).

3. **Set Up the Equation**: Since there are two oxygen atoms in the ion, the total contribution to the oxidation state from both oxygen atoms will be \( 2x \).

4. **Relate to the Ion Charge**: The total oxidation state must equal the charge of the ion. Therefore, we can set up the equation:
\[ 2x = -2 \]

5. **Solve for \( x \)**: To find \( x \), divide both sides of the equation by 2:
\[ x = \frac{-2}{2} = -1 \]

6. **Conclusion**: The oxidation number of oxygen in the \( O_2^{2-} \) ion is \( -1 \).

### Final Answer:
The oxidation number of oxygen in \( O_2^{2-} \) is \( -1 \).

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