In group V ,`(NH_(4))_(2)CO_(3)` is added to precipitate out the carbonate `Na_(2)CO_(3)` is not added because

Options

A. `CaCO_(3)` is soluble in `NaCO_(3)`
B. `MgCO_(3)` will be ppt out in group V
C. `Na_(2)CO_(3)` increases the solublity of group V carbonates
D. All

Answer

To answer the question of why sodium carbonate (Na2CO3) is not added in group V when ammonium carbonate ((NH4)2CO3) is used, we can break down the reasoning step by step:

### Step-by-Step Solution:

1. **Understanding the Role of Carbonates in Group V Analysis**:
- In qualitative inorganic analysis, group V typically includes cations such as calcium (Ca²⁺), magnesium (Mg²⁺), and strontium (Sr²⁺) that can form carbonates.

2. **Use of Ammonium Carbonate**:
- Ammonium carbonate ((NH4)2CO3) is used to provide carbonate ions (CO3²⁻) in a controlled manner. The concentration of carbonate ions from ammonium carbonate is relatively low.

3. **Effect of Sodium Carbonate**:
- If sodium carbonate (Na2CO3) were used instead, it would significantly increase the concentration of carbonate ions in the solution.

4. **Precipitation of Group V Cations**:
- The increased concentration of carbonate ions from sodium carbonate would lead to the precipitation of not only the desired cations in group V but also other cations such as calcium (Ca²⁺), magnesium (Mg²⁺), and strontium (Sr²⁺).

5. **Interference in Detection**:
- The precipitation of these additional cations would interfere with the detection and analysis of the actual group V cations. This would complicate the qualitative analysis and could lead to erroneous results.

6. **Conclusion**:
- Therefore, sodium carbonate is not added because it would cause unwanted precipitations that interfere with the detection of the cations in group V.

### Final Answer:
Sodium carbonate is not added because it increases the concentration of carbonate ions, leading to the precipitation of calcium, magnesium, and strontium ions, which interferes with the detection of group V cations.

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