**False**

**Explanation:**

Not all metals are non-combustible. While many metals have high melting points and are generally resistant to combustion, there are certain metals that can burn or react with oxygen under specific conditions.

**1. Combustible Metals:**

Some metals, known as combustible metals, can burn when exposed to air or other oxidizing agents. These metals include:

- Magnesium (Mg): Magnesium is highly flammable and can catch fire easily when exposed to air or heat. It burns with a bright white flame, producing intense heat.
- Sodium (Na): Sodium is a highly reactive metal that can react violently with water, releasing hydrogen gas and igniting the hydrogen. It can also react with air to form sodium oxide, releasing heat and sometimes causing a fire.
- Potassium (K): Potassium is similar to sodium in its reactivity. It can react vigorously with water, producing hydrogen gas and igniting it. It can also react with air to form potassium oxide, which can ignite in contact with water or moisture.

**2. Metal Powders:**

Even non-combustible metals can become combustible in the form of fine powders or dust. Metal powders have a larger surface area per unit mass, which increases their reactivity. If a sufficient concentration of metal powder is dispersed in the air, it can form a flammable mixture that can ignite and result in a fire or explosion. Some examples of combustible metal powders include aluminum, titanium, and zirconium.

**3. Oxidation Reactions:**

While not combustion in the traditional sense, metals can also undergo oxidation reactions when exposed to oxygen. This can result in the formation of metal oxides and the release of heat. The speed and intensity of these reactions can vary depending on the metal and the conditions. For example, iron rusting is a slow oxidation reaction, while some metals like magnesium can react rapidly with oxygen, releasing a significant amount of heat.

In conclusion, not all metals are non-combustible. Some metals, such as magnesium, sodium, and potassium, can burn when exposed to air or heat. Additionally, metal powders can be combustible, and metals can undergo oxidation reactions in the presence of oxygen. It is important to handle and store metals safely to prevent potential fire hazards.

It's false...