AL2O3 is not a formula for an acid oxide.

The formula for an acid oxide typically involves a non-metal or a metalloid.Out of the options given, only CO2 is a formula for an acid oxide.

The formula for carbon dioxide (CO2) meets the criteria for an acid oxide because it is a non-metallic oxide that can react with water to form anTherefore, the formula for the acid oxide could be:

1. Carbon dioxide (CO2) - This is a covalent compound and a gas at room temperature. It is formed by the reaction of carbon and oxygen.

2. Sulfur dioxide (SO2) - This is also a covalent compound and a gas at room temperature. It is formed by the reaction of sulfur and oxygen.

3. Nitrogen dioxide (NO2) - This is a covalent compound and a reddish-brown gas at room temperature. It is formed by the reaction of nitrogen and oxygen.

4. Phosphorus pentoxide (P2O5) - This is a covalent compound that is solid at room temperature. It is formed by the reaction of phosphorus and oxygen.

The above are some examples of acid oxides. Acid oxides react with water to form acids.