Question

describe the protective layer of oxide with reaction​

Answer 1

I hope you are talking about anodizing of aluminium.

Unlike other metals, corrosion (oxidation) is helpful in aluminium's case.

When aluminium reacts with oxygen, a protective layer of aluminium oxide is formed on its surface, which prevents it from further corrosion and reactions.

The reaction that takes place in its balanced form is as below.

4Al + 3O₂ -----> 2Al₂O₃