Which of the following pair of anions are identified by conc. `H_(2)SO_(4)`.

Options

A. `NO_(3)^(-), CO_(3)^(2-)`
B. `Cl^(-), NO_(3)^(-)`
C. `Br^(-), CO_(3)^(2-)`
D. `CO_(3)^(2-), CH_(3)CO O^(-)`

Answer

To determine which pair of anions can be identified by concentrated sulfuric acid (H₂SO₄), we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Anions in Each Option:**
- Option 1: NO₃⁻ and CO₃²⁻
- Option 2: Cl⁻ and NO₃⁻
- Option 3: Br⁻ and CO₃²⁻
- Option 4: CO₃²⁻ and CH₃COO⁻

2. **Test Each Pair with Concentrated H₂SO₄:**
- **Option 1 (NO₃⁻ and CO₃²⁻):**
- NO₃⁻ (nitrate ion) can be identified by concentrated H₂SO₄, as it produces brown nitrogen dioxide (NO₂) gas upon reaction.
- CO₃²⁻ (carbonate ion) cannot be identified by concentrated H₂SO₄, as it reacts to form carbon dioxide (CO₂) and water, but does not produce a distinct observable change.
- **Conclusion:** Only NO₃⁻ can be identified.

- **Option 2 (Cl⁻ and NO₃⁻):**
- Cl⁻ (chloride ion) can be identified by concentrated H₂SO₄, producing chlorine gas (Cl₂) when reacted.
- NO₃⁻ can also be identified as mentioned above.
- **Conclusion:** Both Cl⁻ and NO₃⁻ can be identified.

- **Option 3 (Br⁻ and CO₃²⁻):**
- Br⁻ (bromide ion) can be identified by concentrated H₂SO₄, producing bromine (Br₂) gas.
- CO₃²⁻ cannot be identified as discussed.
- **Conclusion:** Only Br⁻ can be identified.

- **Option 4 (CO₃²⁻ and CH₃COO⁻):**
- CO₃²⁻ cannot be identified.
- CH₃COO⁻ (acetate ion) also cannot be identified using concentrated H₂SO₄.
- **Conclusion:** Neither can be identified.

3. **Final Answer:**
- The pair of anions that can be identified by concentrated H₂SO₄ is **Cl⁻ and NO₃⁻**.

### Summary:
The correct answer is **Cl⁻ and NO₃⁻** as both can be identified by the addition of concentrated sulfuric acid.