The specles that do not contain peroxlde ions are

Options

A. `PbO_(2)`
B. `H_(2)O_(2)`
C. `KO_(2)`
D. `BaO_(2)`

Answer

To determine which of the given species do not contain peroxide ions, we will analyze each compound based on the presence of the peroxide ion (O2^2-).

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are PbO2, H2O2, K2O2, and BaO2.

2. **Analyze PbO2**:
- The oxidation state of Pb in PbO2 can be calculated as follows:
- Let the oxidation state of Pb be x.
- The oxidation state of O is -2.
- The equation becomes: x + 2(-2) = 0
- Solving this gives: x - 4 = 0 → x = +4.
- Since PbO2 contains normal oxide ions (O^2-), it does not contain peroxide ions.

3. **Analyze H2O2**:
- H2O2 is known as hydrogen peroxide.
- It can be broken down into H+ and O2^2-.
- Thus, H2O2 contains the peroxide ion.

4. **Analyze K2O2**:
- The oxidation state of K in K2O2:
- K is from group 1, so its oxidation state is +1.
- The equation becomes: 2(+1) + 2y = 0, where y is the oxidation state of O.
- This gives: 2 + 2y = 0 → 2y = -2 → y = -1.
- Therefore, K2O2 contains the peroxide ion (O2^2-).

5. **Analyze BaO2**:
- The oxidation state of Ba in BaO2:
- Ba is from group 2, so its oxidation state is +2.
- The equation becomes: +2 + 2(-1) = 0.
- This shows that BaO2 contains the peroxide ion (O2^2-).

6. **Conclusion**:
- From the analysis:
- PbO2 does not contain peroxide ions.
- H2O2, K2O2, and BaO2 do contain peroxide ions.
- Therefore, the species that do not contain peroxide ions is **PbO2**.

### Final Answer:
The species that do not contain peroxide ions are **PbO2**.