Final answer:
The name of the molecular compound P2O3 is diphosphorus trioxide, which follows the naming convention using prefixes to indicate the number of each type of atom.
Step-by-step explanation:
The correct name for the molecular compound P2O3 is diphosphorus trioxide. This follows the naming convention where the prefixes di- and tri- indicate the number of phosphorus and oxygen atoms, respectively. Neither potassium oxide nor phosphate trioxide are correct because the compound does not contain potassium, and the name does not correctly represent the number of phosphorus atoms. Also, triphosphorus dioxide is incorrect as this would imply three phosphorus atoms and two oxygen atoms, which does not match the formula P2O3.