Among `NaO_(2), Na_(2)O_(2), Li_(2)O, CsO_(2)` upaired electron is present in

Options

A. `Na_(2)O_(2)` and `Li_(2)O`
B. `Na_(2)O_(2)`
C. `Li_(2)O`
D. `CsO_(2)` and `NaO_(2)`

Explanation

To determine which of the compounds `NaO2`, `Na2O2`, `Li2O`, and `CsO2` contains unpaired electrons, we will analyze each compound step by step.

### Step 1: Analyze NaO2
- **Composition**: NaO2 consists of Na+ and O2− ions.
- **Na+ Ion**: The sodium ion (Na+) has a noble gas configuration (Neon), meaning it has all electrons paired. Therefore, Na+ is **diamagnetic**.
- **O2− Ion**: The superoxide ion (O2−) has an unpaired electron in its molecular orbital configuration (specifically in the π* 2p orbital). Thus, O2− is **paramagnetic**.
- **Conclusion for NaO2**: Since O2− has an unpaired electron, NaO2 is **paramagnetic** and contains unpaired electrons.

### Step 2: Analyze Na2O2
- **Composition**: Na2O2 consists of Na+ and O2−2 ions (peroxide ion).
- **Na+ Ion**: As previously mentioned, Na+ is **diamagnetic**.
- **O2−2 Ion**: The peroxide ion (O2−2) has all electrons paired in its molecular orbital configuration, making it **diamagnetic**.
- **Conclusion for Na2O2**: Both ions are diamagnetic, so Na2O2 does **not** contain unpaired electrons.

### Step 3: Analyze Li2O
- **Composition**: Li2O consists of Li+ and O2− ions.
- **Li+ Ion**: The lithium ion (Li+) has a noble gas configuration (Helium), thus it is **diamagnetic**.
- **O2− Ion**: The oxide ion (O2−) is also diamagnetic as it has all electrons paired (Neon configuration).
- **Conclusion for Li2O**: Both ions are diamagnetic, so Li2O does **not** contain unpaired electrons.

### Step 4: Analyze CsO2
- **Composition**: CsO2 consists of Cs+ and O2− ions.
- **Cs+ Ion**: The cesium ion (Cs+) is **diamagnetic** due to its noble gas configuration (Xe).
- **O2− Ion**: The superoxide ion (O2−) has an unpaired electron in its molecular orbital configuration, making it **paramagnetic**.
- **Conclusion for CsO2**: Since O2− has an unpaired electron, CsO2 is **paramagnetic** and contains unpaired electrons.

### Final Conclusion
Among the compounds analyzed:
- **NaO2** and **CsO2** contain unpaired electrons.
- **Na2O2** and **Li2O** do not contain unpaired electrons.

Thus, the correct answer is that unpaired electrons are present in **NaO2** and **CsO2**.