`Fe(OH)_(3)` and `Al(OH)_(3)` ppt. can be separated by (a) ___when (b)___ becomes soluble due to the formation of (c ) ___ and (d) ____ remain insoluble.

Answer

To solve the question regarding the separation of Fe(OH)₃ and Al(OH)₃ precipitates, we will fill in the blanks step by step.

### Step-by-Step Solution:

1. **Identify the precipitates**: We have two hydroxides, Fe(OH)₃ (ferric hydroxide) and Al(OH)₃ (aluminum hydroxide), which are both insoluble in water.

2. **Choose a reagent for separation**: To separate these two precipitates, we can use sodium hydroxide (NaOH).

- **Answer for (a)**: Sodium hydroxide

3. **Determine the solubility change**: When sodium hydroxide is added, aluminum hydroxide (Al(OH)₃) becomes soluble. This is due to the formation of a soluble complex.

- **Answer for (b)**: Aluminum hydroxide

4. **Identify the soluble compound formed**: The soluble compound formed from aluminum hydroxide in the presence of sodium hydroxide is sodium meta-aluminate (NaAlO₂).

- **Answer for (c)**: Sodium meta-aluminate

5. **Confirm the behavior of the other precipitate**: Ferric hydroxide (Fe(OH)₃) remains insoluble in sodium hydroxide.

- **Answer for (d)**: Ferric hydroxide

### Final Answers:
- (a) Sodium hydroxide
- (b) Aluminum hydroxide
- (c) Sodium meta-aluminate
- (d) Ferric hydroxide