An amphoteric oxide is an oxide that can react with both acids and bases. To show that an oxide is amphoteric, you can test its reaction with both a strong acid and a strong base.

Here's a common approach:

1. Acid Test:

- Use a strong acid like hydrochloric acid (HCl).

- If the oxide reacts with the acid, it will dissolve, often forming a salt and water.

- Example: Aluminum oxide (Al₂O₃) reacts with HCl:

```

Al₂O₃ (s) + 6 HCl (aq) → 2 AlCl₃ (aq) + 3 H₂O (l)

```

2. Base Test:

- Use a strong base like sodium hydroxide (NaOH).

- If the oxide reacts with the base, it will also dissolve, often forming a salt and water.

- Example: Aluminum oxide (Al₂O₃) reacts with NaOH:

```

Al₂O₃ (s) + 2 NaOH (aq) + 3 H₂O (l) → 2 Na[Al(OH)₄] (aq)

```

Other important considerations:

* Solubility: Sometimes, the reaction with an acid or base might be slow or incomplete. You may need to heat the mixture or use a more concentrated solution to observe a reaction.

* Visual Observations: Look for changes in color, the formation of a precipitate, or the evolution of gas, which can indicate a reaction.

Examples of Amphoteric Oxides:

* Aluminum oxide (Al₂O₃)

* Zinc oxide (ZnO)

* Lead oxide (PbO)

* Tin oxide (SnO)

* Chromium oxide (Cr₂O₃)

Note: Not all oxides are amphoteric. Many oxides are either acidic or basic, depending on the non-metal or metal they contain.