There is no single symbol for "metal oxide". Metal oxides are a large and diverse group of compounds, each with its own unique chemical formula.

Here's how to understand the symbols:

* Metal: Represented by its chemical symbol (e.g., Fe for iron, Cu for copper, Na for sodium).

* Oxygen: Represented by the symbol "O".

* Subscript: Indicates the number of atoms of each element in the compound. This subscript is determined by the chemical reaction that forms the oxide and the valency of the metal.

Examples:

* Iron oxide (rust): Fe₂O₃ (two iron atoms and three oxygen atoms)

* Copper oxide: CuO (one copper atom and one oxygen atom)

* Sodium oxide: Na₂O (two sodium atoms and one oxygen atom)

General Formula:

The general formula for metal oxides is M₂Oₓ where:

* M represents the metal

* x is the number of oxygen atoms, which varies depending on the metal and its oxidation state.

So, instead of a single symbol, metal oxides are represented by their specific chemical formulas, reflecting the unique combination of metal and oxygen atoms in each compound.