Which of the following compounds is a peroxide ?

Options

A. `KO_(2)`
B. `BaO_(2)`
C. `MnO_(2)`
D. `NO_(2)`

Answer

To determine which of the given compounds is a peroxide, we need to analyze each compound based on its chemical formula and the oxidation states of the oxygen present in it.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- Potassium superoxide (KO2)
- Barium peroxide (BaO2)
- Manganese dioxide (MnO2)
- Nitrogen dioxide (NO2)

2. **Understanding Peroxides**: A peroxide is a compound that contains an oxygen-oxygen single bond (O-O) and typically has the peroxide ion (O2^2-) where the oxidation state of each oxygen is -1.

3. **Analyzing Each Compound**:
- **Potassium Superoxide (KO2)**:
- In KO2, the superoxide ion (O2^-) is present, where one of the oxygen atoms has an oxidation state of -1/2. This does not qualify as a peroxide.

- **Barium Peroxide (BaO2)**:
- In BaO2, the barium ion (Ba^2+) is paired with the peroxide ion (O2^2-). Here, each oxygen has an oxidation state of -1, which confirms that BaO2 is indeed a peroxide.

- **Manganese Dioxide (MnO2)**:
- In MnO2, manganese is in the +4 oxidation state, and the oxygen is in the -2 oxidation state. This is a typical oxide, not a peroxide.

- **Nitrogen Dioxide (NO2)**:
- In NO2, nitrogen is in the +4 oxidation state, and oxygen is in the -2 oxidation state. This is also a typical oxide, not a peroxide.

4. **Conclusion**: Among the given compounds, only **Barium Peroxide (BaO2)** is a peroxide.

### Final Answer:
The compound that is a peroxide is **Barium Peroxide (BaO2)**.