Which of the following is not an amphoteric ion?

Options

A. 1. `Al^(3+)`
B. 2. `Cr^(3+)`
C. 3. `Fe^(2+)`
D. 4. `Zn^(2+)`

Answer

To determine which of the following ions is not an amphoteric ion, we need to analyze the behavior of each ion with respect to acids and bases. Amphoteric ions are those that can react with both acids and bases.

### Step-by-Step Solution:

1. **Understand Amphoteric Ions**: Amphoteric ions can react with acids to form salts and with bases to form complexes or hydroxides.

2. **Analyze Each Ion**:
- **Aluminum Ion (Al³⁺)**:
- Reacts with acids (e.g., H₂SO₄) to form aluminum sulfate and hydrogen gas.
- Reacts with bases (e.g., NaOH) to form aluminum hydroxide and sodium ions.
- Conclusion: Al³⁺ is amphoteric.

- **Chromium Ion (Cr³⁺)**:
- Reacts with acids (e.g., H₂SO₄) to form chromium sulfate.
- Reacts with bases to form chromium hydroxide.
- Conclusion: Cr³⁺ is amphoteric.

- **Iron Ion (Fe²⁺)**:
- Reacts with acids to form iron(II) sulfate.
- Does not react with bases; it primarily reacts with acids.
- Conclusion: Fe²⁺ is **not** amphoteric.

- **Zinc Ion (Zn²⁺)**:
- Reacts with acids (e.g., HCl) to form zinc chloride.
- Reacts with bases (e.g., NaOH) to form zinc hydroxide or sodium zincate.
- Conclusion: Zn²⁺ is amphoteric.

3. **Identify the Non-Amphoteric Ion**: Based on the analysis, the ion that does not exhibit amphoteric behavior is **Fe²⁺**.

### Final Answer:
**Fe²⁺ is not an amphoteric ion.**

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