Which of the following salt does give positive test for nitrate ion?

Options

A. `KNO_(3)`
B. `NaNO_(3)`
C. `Mg(NO_(3))_(2)`
D. None of these

Answer

To determine which of the following salts gives a positive test for nitrate ions, we need to analyze each of the salts provided: KNO3 (potassium nitrate), NaNO3 (sodium nitrate), and Mg(NO3)2 (magnesium nitrate).

### Step-by-Step Solution:

1. **Understanding the Salts**:
- We have three salts: KNO3, NaNO3, and Mg(NO3)2.
- All of these salts contain the nitrate ion (NO3^-).

2. **Dissociation of Salts in Aqueous Solution**:
- When these salts are dissolved in water, they dissociate into their constituent ions.
- KNO3 dissociates into K^+ and NO3^- ions.
- NaNO3 dissociates into Na^+ and NO3^- ions.
- Mg(NO3)2 dissociates into Mg^2+ and 2 NO3^- ions.

3. **Presence of Nitrate Ion**:
- Since all three salts produce the nitrate ion (NO3^-) upon dissociation, they will all give a positive test for nitrate ions in solution.
- KNO3 provides 1 NO3^- ion, NaNO3 provides 1 NO3^- ion, and Mg(NO3)2 provides 2 NO3^- ions.

4. **Conclusion**:
- Therefore, all three salts (KNO3, NaNO3, and Mg(NO3)2) will give a positive test for nitrate ions.

### Final Answer:
All three salts (KNO3, NaNO3, and Mg(NO3)2) give a positive test for nitrate ions.

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