Which anion does not liberate any gas with dilute as well as conc. `H_(2)SO_(4)`.

Options

A. `NO_(2)^(-)`
B. `NO_(3)^(-)`
C. `SO_(3)^(2-)`
D. `SO_(4)^(2-)`

Answer

To determine which anion does not liberate any gas when treated with dilute and concentrated sulfuric acid (H₂SO₄), we need to analyze the behavior of various anions in the presence of H₂SO₄.

### Step-by-Step Solution:

1. **Identify the Anions**: The question implies that there are several anions to consider. Common anions that might be tested include sulfate (SO₄²⁻), nitrate (NO₃⁻), nitrite (NO₂⁻), and bisulfite (HSO₃⁻).

2. **Understand the Reaction with Dilute H₂SO₄**:
- **Sulfate (SO₄²⁻)**: When sulfate ions react with dilute H₂SO₄, no gas is liberated.
- **Nitrate (NO₃⁻)**: Nitrate ions react with dilute H₂SO₄ to produce nitrogen dioxide (NO₂) gas.
- **Nitrite (NO₂⁻)**: Nitrite ions react with dilute H₂SO₄ to produce nitrogen dioxide (NO₂) gas as well.
- **Bisulfite (HSO₃⁻)**: Bisulfite ions react with dilute H₂SO₄ to produce sulfur dioxide (SO₂) gas.

3. **Understand the Reaction with Concentrated H₂SO₄**:
- **Sulfate (SO₄²⁻)**: Similar to dilute H₂SO₄, sulfate ions do not liberate any gas when treated with concentrated H₂SO₄.
- **Nitrate (NO₃⁻)**: Concentrated H₂SO₄ will oxidize nitrate ions to produce nitrogen dioxide (NO₂) gas.
- **Nitrite (NO₂⁻)**: Concentrated H₂SO₄ will oxidize nitrite ions to produce nitrogen dioxide (NO₂) gas.
- **Bisulfite (HSO₃⁻)**: Concentrated H₂SO₄ will oxidize bisulfite ions to produce sulfur dioxide (SO₂) gas.

4. **Conclusion**: Based on the analysis, the only anion that does not liberate any gas with both dilute and concentrated H₂SO₄ is sulfate (SO₄²⁻).

### Final Answer:
The anion that does not liberate any gas with dilute as well as concentrated H₂SO₄ is **sulfate (SO₄²⁻)**.