The reagents `NH_(4)Cl` and `NH_(3)` will precipitate :

Options

A. `Ca^(2+)`
B. `Al^(2+)`
C. `Bi^(2+)`
D. `Mg^(2+)`

Explanation

To determine which ions will precipitate when using the reagents NH4Cl (ammonium chloride) and NH3 (ammonia), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reagents**:
- NH4Cl is a source of NH4+ ions and Cl- ions in solution.
- NH3 is a weak base that can react with water to produce NH4+ and OH- ions.

2. **Formation of Hydroxides**:
- When NH3 is added to a solution containing metal ions, it can lead to the formation of metal hydroxides.
- The hydroxides of certain metal ions are insoluble in water and will precipitate out of the solution.

3. **Identifying the Metal Ions**:
- Common metal ions that can form insoluble hydroxides with NH3 include aluminum (Al^3+) and bismuth (Bi^3+).
- The hydroxides formed are:
- Aluminum hydroxide: Al(OH)3
- Bismuth hydroxide: Bi(OH)3

4. **Precipitation Reaction**:
- The addition of NH4Cl and NH3 to a solution containing Al^3+ and Bi^3+ will lead to the precipitation of their respective hydroxides:
- Al^3+ + 3OH- → Al(OH)3 (s)
- Bi^3+ + 3OH- → Bi(OH)3 (s)

5. **Conclusion**:
- Therefore, both aluminum ions (Al^3+) and bismuth ions (Bi^3+) will precipitate as their hydroxides when NH4Cl and NH3 are present.

### Final Answer:
The reagents NH4Cl and NH3 will precipitate aluminum ions (Al^3+) and bismuth ions (Bi^3+) as their hydroxides.

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