`Fe(OH)_(3)` and `Cr(OH)_(3)` precipitates can be completely separated
by `:`

Options

A. `Aq.NH_(3)`
B. `HCl`
C. `NaOH//H_(2)O_(2)`
D. `H_(2)SO_(4)`

Explanation

To separate the precipitates of Fe(OH)₃ and Cr(OH)₃, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Precipitates**:
- We have two hydroxides: Iron(III) hydroxide, Fe(OH)₃, and Chromium(III) hydroxide, Cr(OH)₃.

2. **Consider the Solubility in Acids**:
- Both Fe(OH)₃ and Cr(OH)₃ are soluble in strong acids (like HCl and H₂SO₄). Therefore, using these acids will not help in separating the two hydroxides as they will dissolve.

3. **Evaluate Aqueous Ammonia**:
- Aqueous ammonia can dissolve Cr(OH)₃ partially but does not affect Fe(OH)₃, which remains insoluble. However, since Cr(OH)₃ is only partially soluble, this method is not effective for complete separation.

4. **Consider NaOH with H₂O₂**:
- When NaOH is added along with hydrogen peroxide (H₂O₂), Cr(OH)₃ reacts to form soluble chromate ions (CrO₄²⁻), which results in a yellow solution. This means Cr(OH)₃ can be completely dissolved in this solution.
- On the other hand, Fe(OH)₃ remains insoluble in this alkaline medium, allowing for the complete separation of the two hydroxides.

5. **Conclusion**:
- The best reagent combination for the complete separation of Fe(OH)₃ and Cr(OH)₃ is **NaOH with H₂O₂**.

### Final Answer:
Fe(OH)₃ and Cr(OH)₃ precipitates can be completely separated by **NaOH with H₂O₂**.

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