The metal that can form a barrier layer of oxide on its surface is aluminium.

Explanation:

Aluminium is a highly reactive metal and readily reacts with oxygen in the air to form a thin layer of aluminium oxide on its surface. This layer acts as a barrier, preventing further reaction between aluminium and oxygen.

Here is a detailed explanation of why aluminium forms a barrier layer of oxide on its surface:

1. Reactivity of Aluminium:
Aluminium is a highly reactive metal. It readily reacts with oxygen in the air to form aluminium oxide. This reaction is known as oxidation.

2. Formation of Aluminium Oxide:
When aluminium reacts with oxygen, it forms a thin layer of aluminium oxide (Al2O3) on its surface. This oxide layer is firmly adhered to the metal and acts as a protective barrier.

3. Properties of Aluminium Oxide:
Aluminium oxide is a hard and transparent compound. It has a high melting point and is chemically stable. These properties make the oxide layer resistant to further oxidation and corrosion.

4. Protective Barrier:
The oxide layer acts as a barrier between the metal and the surrounding environment. It prevents the metal from coming into direct contact with air or moisture, which could lead to further oxidation or corrosion.

5. Self-Healing Nature:
If the oxide layer is scratched or damaged, it immediately reacts with the surrounding air to reform the oxide layer. This self-healing property of aluminium oxide ensures the continued protection of the metal surface.

6. Application of Aluminium Oxide:
The barrier layer of aluminium oxide is highly desirable in many practical applications. It is used in the construction of aircraft, automobiles, and other structures where corrosion resistance is essential. Aluminium foil, which is widely used for packaging, also relies on the protective oxide layer.

In conclusion, aluminium is the metal that forms a barrier layer of oxide on its surface. This oxide layer acts as a protective barrier, preventing further oxidation and corrosion of the metal. The self-healing nature of the oxide layer ensures the continued protection of the aluminium surface.