Which of the following show amphoteric behaviour?

Options

A. `Zn(OH)_(2)`
B. `Be(OH)_(2)`
C. `Al(OH)_(3)`
D. `Pb(OH)_(2)`

Answer

To determine which of the given compounds exhibit amphoteric behavior, we need to understand what amphoteric means. Amphoteric substances can react with both acids and bases, displaying dual behavior depending on the conditions.

### Step-by-Step Solution:

1. **Define Amphoteric Behavior**:
- Amphoteric substances are those that can react with both acids and bases. This means they can either donate protons (act as an acid) or accept protons (act as a base).

2. **Identify Common Amphoteric Compounds**:
- Common amphoteric hydroxides include:
- Aluminum hydroxide (Al(OH)₃)
- Zinc hydroxide (Zn(OH)₂)
- Beryllium hydroxide (Be(OH)₂)
- Lead hydroxide (Pb(OH)₂)

3. **Reactions of Amphoteric Hydroxides**:
- **Aluminum Hydroxide (Al(OH)₃)**:
- As a base:
\[ \text{Al(OH)}_3 + 3 \text{HCl} \rightarrow \text{AlCl}_3 + 3 \text{H}_2\text{O} \]
- As an acid:
\[ \text{Al(OH)}_3 + \text{NaOH} \rightarrow \text{Na[Al(OH)}_4] \]

- **Zinc Hydroxide (Zn(OH)₂)**:
- As a base:
\[ \text{Zn(OH)}_2 + 2 \text{HCl} \rightarrow \text{ZnCl}_2 + 2 \text{H}_2\text{O} \]
- As an acid:
\[ \text{Zn(OH)}_2 + 2 \text{NaOH} \rightarrow \text{Na}_2[\text{Zn(OH)}_4] \]

- **Beryllium Hydroxide (Be(OH)₂)**:
- As a base:
\[ \text{Be(OH)}_2 + 2 \text{HCl} \rightarrow \text{BeCl}_2 + 2 \text{H}_2\text{O} \]
- As an acid:
\[ \text{Be(OH)}_2 + 2 \text{NaOH} \rightarrow \text{Na}_2[\text{Be(OH)}_4] \]

- **Lead Hydroxide (Pb(OH)₂)**:
- As a base:
\[ \text{Pb(OH)}_2 + 2 \text{HCl} \rightarrow \text{PbCl}_2 + 2 \text{H}_2\text{O} \]
- As an acid:
\[ \text{Pb(OH)}_2 + 2 \text{NaOH} \rightarrow \text{Na}_2[\text{Pb(OH)}_4] \]

4. **Conclusion**:
- All the compounds listed (zinc hydroxide, beryllium hydroxide, aluminum hydroxide, and lead hydroxide) exhibit amphoteric behavior as they can react with both acids and bases.

### Final Answer:
All options (A, B, C, D) show amphoteric behavior.

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