Which of the following is peroxide?

Options

A. `K_2O`
B. `K_2O_2`
C. `KO_2`
D. None

Answer

To determine which of the given compounds is a peroxide, we need to analyze each option based on the oxidation state of oxygen. A peroxide is characterized by having an O-O linkage and the oxidation state of oxygen in peroxides is -1.

### Step-by-Step Solution:

1. **Understanding Peroxide**:
- A peroxide contains an O-O bond, and the oxidation state of oxygen in peroxides is -1.

2. **Analyzing K2O**:
- K2O consists of potassium (K) and oxygen (O).
- Potassium has an oxidation state of +1.
- Let the oxidation state of oxygen be X.
- The equation can be set up as:
\[ 2(+1) + X = 0 \implies 2 + X = 0 \implies X = -2 \]
- Since the oxidation state of oxygen is -2, K2O is an oxide, not a peroxide.

3. **Analyzing K2O2**:
- K2O2 also consists of potassium and oxygen.
- Let the oxidation state of oxygen be Y.
- The equation can be set up as:
\[ 2(+1) + 2Y = 0 \implies 2 + 2Y = 0 \implies 2Y = -2 \implies Y = -1 \]
- Since the oxidation state of oxygen is -1, K2O2 is a peroxide.

4. **Analyzing KO2**:
- KO2 consists of potassium and oxygen.
- Let the oxidation state of oxygen be Z.
- The equation can be set up as:
\[ +1 + 2Z = 0 \implies 1 + 2Z = 0 \implies 2Z = -1 \implies Z = -\frac{1}{2} \]
- Since the oxidation state of oxygen is -1/2, KO2 is a superoxide, not a peroxide.

5. **Conclusion**:
- Based on the analysis, K2O is an oxide, K2O2 is a peroxide, and KO2 is a superoxide.
- Therefore, the correct answer is **B (K2O2)**.