`Fe(OH)_(3)` and `Cr(OH)_(3)` ppt are sepurated by

Options

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

Answer

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

### Step-by-Step Solution:

1. **Identify the Precipitates**:
We have two precipitates: Ferric hydroxide (Fe(OH)₃), which is brown, and Chromium hydroxide (Cr(OH)₃), which is green.

2. **Use of Reagents**:
To separate these two hydroxides, we will use sodium hydroxide (NaOH) and hydrogen peroxide (H₂O₂) as our reagents.

3. **Reaction with NaOH**:
When NaOH is added to the mixture containing both precipitates, it will not affect the ferric hydroxide significantly. However, it will help in the solubilization of chromium hydroxide.

4. **Formation of Chromium Complex**:
In the presence of NaOH, chromium hydroxide (Cr(OH)₃) reacts with hydroxide ions (OH⁻) to form a complex ion, specifically Cr(OH)₄⁻.

5. **Addition of Hydrogen Peroxide**:
Now, when hydrogen peroxide (H₂O₂) is added to the alkaline solution, it reacts with the chromium complex (Cr(OH)₄⁻) and converts it into chromate ions (CrO₄²⁻), which are yellow in color.

6. **Resulting Solutions**:
As a result, we obtain a yellow solution of chromate ions while the brown precipitate of ferric hydroxide remains unchanged.

7. **Conclusion**:
Thus, the separation of Fe(OH)₃ and Cr(OH)₃ can be effectively achieved using NaOH and H₂O₂.

### Final Answer:
The precipitates of Fe(OH)₃ and Cr(OH)₃ can be separated by using **sodium hydroxide (NaOH) and hydrogen peroxide (H₂O₂)**.

---