Which is not amphoteric?

Options

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

Explanation

To determine which of the given options is not amphoteric, we need to analyze the behavior of each ion or element in both acidic and basic environments. Amphoteric substances can react with both acids and bases.

### Step-by-Step Solution:

1. **Understand the Definition of Amphoteric:**
- Amphoteric substances can react with both acids and bases. This means they can either donate or accept protons (H⁺ ions) depending on the environment.

2. **Analyze Al³⁺:**
- Al³⁺ reacts with hydrochloric acid (HCl) to form aluminum chloride (AlCl₃).
- Al³⁺ also reacts with sodium hydroxide (NaOH) to form aluminum hydroxide (Al(OH)₃).
- Since Al³⁺ reacts with both an acid and a base, it is amphoteric.

3. **Analyze Cr³⁺:**
- Cr³⁺ reacts with HCl to form chromium(III) chloride (CrCl₃).
- Cr³⁺ also reacts with NaOH to form sodium chromate (Na₂CrO₄).
- Since Cr³⁺ reacts with both an acid and a base, it is amphoteric.

4. **Analyze Fe:**
- Iron (Fe) reacts with HCl to form iron(III) chloride (FeCl₃).
- However, Fe does not react with NaOH under normal conditions, indicating that it does not react with bases.
- Therefore, iron is not amphoteric as it only reacts with acids.

5. **Analyze Zn²⁺:**
- Zn²⁺ reacts with HCl to form zinc chloride (ZnCl₂).
- Zn²⁺ also reacts with NaOH to form zinc hydroxide (Zn(OH)₂).
- Since Zn²⁺ reacts with both an acid and a base, it is amphoteric.

6. **Conclusion:**
- Among the options analyzed, only Fe does not exhibit amphoteric behavior as it does not react with bases. Therefore, the answer is **Fe**.

### Final Answer:
The element that is not amphoteric is **Fe** (option C).