`Na_(2)O_(2)`

Options

A. is diamagnetic in nature
B. is salt of dibasic acid `H_(2)O_(2)`
C. oxidizes `Cr^(3+)` (green) to `CrO_(4)^(2-)` (yellow)
D. all are correct properties of `Na_(2)O_(2)`

Answer

To solve the question regarding the properties of sodium peroxide (Na₂O₂), we will analyze each statement provided and confirm their validity step by step.

### Step 1: Determine if Na₂O₂ is diamagnetic.
- **Definition of Diamagnetic**: A substance is diamagnetic if all its electrons are paired, resulting in no net magnetic moment.
- **Electron Count**:
- Sodium (Na) has an atomic number of 11, meaning it has 11 electrons.
- Therefore, two sodium atoms contribute: \(2 \times 11 = 22\) electrons.
- Oxygen (O) has an atomic number of 8, meaning it has 8 electrons.
- Since there are two oxygen atoms in Na₂O₂, they contribute: \(2 \times 8 = 16\) electrons.
- **Total Electrons**:
- Total = \(22 + 16 = 38\) electrons.
- **Conclusion**: Since 38 is an even number, all electrons can be paired, confirming that Na₂O₂ is indeed diamagnetic.

### Step 2: Confirm if Na₂O₂ is a salt of dibasic acid H₂O₂.
- **Definition of Dibasic Acid**: A dibasic acid can donate two protons (H⁺ ions) per molecule.
- **Formation of Na₂O₂**: Sodium peroxide can be formed from the hydrolysis of hydrogen peroxide (H₂O₂):
\[ 2 \text{Na}_2\text{O}_2 + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2\text{O}_2 \]
- **Conclusion**: Since Na₂O₂ is derived from H₂O₂, which is a dibasic acid, this statement is true.

### Step 3: Check if Na₂O₂ oxidizes Cr³⁺ (green) to CrO₄²⁻ (yellow).
- **Oxidation Reaction**: Sodium peroxide can oxidize chromium from +3 to +6 oxidation state:
\[ \text{Na}_2\text{O}_2 + \text{Cr}_2\text{O}_3 + \text{H}_2\text{O} \rightarrow 6 \text{Na}^+ + 2 \text{CrO}_4^{2-} + 2 \text{OH}^- \]
- **Oxidation States**:
- In Cr₂O₃, the oxidation state of Cr is +3.
- In CrO₄²⁻, the oxidation state of Cr is +6.
- **Color Change**: Cr₂O₃ is green, and CrO₄²⁻ is yellow.
- **Conclusion**: The oxidation of Cr³⁺ to CrO₄²⁻ is confirmed, making this statement true.

### Final Conclusion:
All three statements regarding Na₂O₂ are correct:
1. Na₂O₂ is diamagnetic in nature.
2. Na₂O₂ is a salt of the dibasic acid H₂O₂.
3. Na₂O₂ oxidizes Cr³⁺ (green) to CrO₄²⁻ (yellow).