4 Fe(s) + 3 O₂(g) → 2 Fe₂O₃(s)

Here's what the equation represents:

* Fe(s): Solid iron (Fe)

* O₂(g): Gaseous oxygen (O₂)

* Fe₂O₃(s): Solid iron(III) oxide (rust)

Explanation:

* When iron is exposed to air (which contains oxygen), a chemical reaction occurs.

* Iron atoms lose electrons and combine with oxygen atoms to form iron(III) oxide, commonly known as rust.

* This reaction is an oxidation reaction, where iron is oxidized (loses electrons) and oxygen is reduced (gains electrons).

The process of rusting is a slow and gradual process that can be accelerated by the presence of moisture and salt.