Which element among the following cannot form an amphoteric oxide ?

Options

A. Al
B. Sn
C. Sb
D. P

Answer

To determine which element among the given options cannot form an amphoteric oxide, we first need to understand what amphoteric oxides are. Amphoteric oxides are oxides that can react with both acids and bases to produce salt and water.

### Step-by-Step Solution:

1. **Define Amphoteric Oxides**:
Amphoteric oxides are those that can react with both acids and bases. This means they can act as either an acid or a base depending on the reacting species.

2. **Analyze the Options**:
We will evaluate each element given in the options to see if they form amphoteric oxides.

- **Aluminum (Al)**:
Aluminum oxide (Al₂O₃) is known to be amphoteric. It reacts with acids to form aluminum salts and with bases to form aluminate ions.
- Reaction with acid:
\[ Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O \]
- Reaction with base:
\[ Al_2O_3 + 2NaOH + 3H_2O \rightarrow 2NaAl(OH)_4 \]

- **Tin (Sn)**:
Tin oxide (SnO₂) is also amphoteric. It reacts with acids and bases.
- Reaction with acid:
\[ SnO_2 + 4HCl \rightarrow SnCl_4 + 2H_2O \]
- Reaction with base:
\[ SnO_2 + 2NaOH + 2H_2O \rightarrow Na_2[Sn(OH)_4] \]

- **Antimony (Sb)**:
Antimony oxide (Sb₂O₃) is amphoteric as well. It reacts with both acids and bases.
- Reaction with acid:
\[ Sb_2O_3 + 6HCl \rightarrow 2SbCl_3 + 3H_2O \]
- Reaction with base:
\[ Sb_2O_3 + 6NaOH \rightarrow 2Na_3Sb(OH)_6 \]

- **Phosphorus (P)**:
Phosphorus oxide (P₂O₅) is not amphoteric; it is acidic. It reacts with water to form phosphoric acid and does not react with bases.
- Reaction with water:
\[ P_2O_5 + 3H_2O \rightarrow 2H_3PO_4 \]

3. **Conclusion**:
Among the given elements, phosphorus does not form an amphoteric oxide. Instead, it forms an acidic oxide.

### Final Answer:
Phosphorus (P) cannot form an amphoteric oxide.

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