For testing sodium carbonate solution for the presence of sulphate ions as impurities one should add :

Options

A. Excess hydrochloric acid and silver nitrate solution
B. Excess sulpharic acid and silver nitrate solution
C. Excess nitric acid and silver nitrate solution
D. Excess hydrochloric acid and barium chloride solution

Explanation

To test sodium carbonate solution for the presence of sulfate ions as impurities, follow these steps:

### Step-by-Step Solution:

1. **Identify the Problem**: We need to test a sodium carbonate (Na2CO3) solution for sulfate ions (SO4^2-) as impurities.

2. **Choose the Reagents**: The appropriate reagents for this test are hydrochloric acid (HCl) and barium chloride (BaCl2).

3. **Neutralize Sodium Carbonate**:
- Add excess hydrochloric acid to the sodium carbonate solution.
- The reaction will be:
\[ \text{Na}_2\text{CO}_3 + 2 \text{HCl} \rightarrow 2 \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 \]
- This reaction neutralizes the sodium carbonate, producing sodium chloride, water, and carbon dioxide gas.

4. **Add Barium Chloride**:
- After neutralization, add barium chloride solution to the mixture.
- The sulfate ions (if present) will react with barium chloride to form barium sulfate (BaSO4), which is a white precipitate:
\[ \text{BaCl}_2 + \text{SO}_4^{2-} \rightarrow \text{BaSO}_4 \downarrow + 2 \text{Cl}^- \]

5. **Observe the Result**:
- If a white precipitate forms, it indicates the presence of sulfate ions in the sodium carbonate solution.

6. **Conclusion**: The presence of a white precipitate confirms that sulfate ions are present as impurities in the sodium carbonate solution.

### Final Answer:
To test sodium carbonate solution for the presence of sulfate ions as impurities, one should add excess hydrochloric acid and barium chloride solution.