Ammonium molybdate is used to test the radical

Options

A. `PO_(4)^(3-)`
B. `AsO_(4)^(3-)`
C. `Cu^(2+)`
D. `Ag^(o+)`

Explanation

**Step-by-Step Solution:**

1. **Understanding Ammonium Molybdate**: Ammonium molybdate is a chemical compound represented as \( \text{(NH}_4\text{)}_2\text{MoO}_4 \). It is commonly used as a reagent in qualitative analysis.

**Hint**: Remember the chemical formula of ammonium molybdate and its components.

2. **Identifying the Radicals Tested**: Ammonium molybdate is primarily used to test for the presence of phosphate ions (\( \text{PO}_4^{3-} \)) and arsenate ions (\( \text{AsO}_4^{3-} \)).

**Hint**: Focus on the specific ions that ammonium molybdate can detect.

3. **Procedure for Testing**: To test for phosphate or arsenate, the sample is first treated with sodium peroxide to oxidize any phosphorus present to phosphate. This step ensures that phosphorus is in the correct form for detection.

**Hint**: Understand the importance of oxidation in the testing process.

4. **Boiling with Nitric Acid**: The solution is then boiled with nitric acid. This step helps to further prepare the solution for the addition of ammonium molybdate by ensuring that it is in a suitable acidic environment.

**Hint**: Remember the role of nitric acid in preparing the sample.

5. **Adding Ammonium Molybdate**: After boiling, ammonium molybdate is added to the solution. If phosphate or arsenate ions are present, a yellow precipitate will form.

**Hint**: Pay attention to the color change that indicates a positive test.

6. **Interpreting the Results**: The formation of a yellow precipitate confirms the presence of phosphate ions (\( \text{PO}_4^{3-} \)) or arsenate ions (\( \text{AsO}_4^{3-} \)). Thus, ammonium molybdate is a specific reagent for detecting these radicals.

**Hint**: Remember that the yellow precipitate is a key indicator of the presence of the tested ions.

**Conclusion**: Ammonium molybdate is used to test for the presence of phosphate ions (\( \text{PO}_4^{3-} \)) and arsenate ions (\( \text{AsO}_4^{3-} \)), confirmed by the formation of a yellow precipitate upon testing.

---