Which of the following is not soluble in NaOH?

Options

A. `Fe(OH)_(3)`
B. `Zn(OH)_(2)`
C. `Al(OH)_(3)`
D. `Sn(OH)_(2)`

Explanation

To determine which of the following compounds is not soluble in NaOH, we will analyze the solubility of each compound in sodium hydroxide (NaOH).

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we need to analyze for solubility in NaOH are:
- Zn(OH)₂ (Zinc hydroxide)
- Al(OH)₃ (Aluminum hydroxide)
- Sn(OH)₂ (Tin(II) hydroxide)
- Fe(OH)₃ (Iron(III) hydroxide)

2. **Check Solubility of Each Compound**:
- **Zinc Hydroxide (Zn(OH)₂)**:
- When Zn(OH)₂ reacts with NaOH, it forms Na₂ZnO₂ (sodium zincate) and water.
- **Conclusion**: Zn(OH)₂ is soluble in NaOH.

- **Aluminum Hydroxide (Al(OH)₃)**:
- When Al(OH)₃ reacts with NaOH, it forms NaAlO₂ (sodium aluminate) and water.
- **Conclusion**: Al(OH)₃ is soluble in NaOH.

- **Tin(II) Hydroxide (Sn(OH)₂)**:
- When Sn(OH)₂ reacts with NaOH, it forms Na₂SnO₂ (sodium stannate) and water.
- **Conclusion**: Sn(OH)₂ is soluble in NaOH.

- **Iron(III) Hydroxide (Fe(OH)₃)**:
- Fe(OH)₃ does not react with NaOH to form any soluble compound. There is no formation of a precipitate, indicating that it is not soluble in NaOH.
- **Conclusion**: Fe(OH)₃ is not soluble in NaOH.

3. **Final Answer**: Among the given compounds, **Fe(OH)₃ (Iron(III) hydroxide)** is the one that is not soluble in NaOH.