What does P2O3 stand for?

P2O3 is correctly named diphosphorous trioxide because it consists of two phosphorus (P) atoms and three oxygen (O) atoms. The prefix 'di-' indicates the presence of two phosphorus atoms, while 'tri-' indicates three oxygen atoms in the compound.

In chemical nomenclature, the first part of the name reflects the number of atoms of the first element in the molecule, which, in this case, is phosphorus. The second part of the name indicates the number of oxygen atoms bonded to the phosphorus. The 'oxide' refers specifically to the oxygen component.

The other options contain elements or prefixes that do not accurately describe the composition of P2O3. For example, 'tetraoxide' implies the presence of four oxygen atoms, which does not match the formula, while 'sulfide' indicates the presence of sulfur instead of oxygen. Thus, the use of 'diphosphorous trioxide' precisely captures the correct number of phosphorus and oxygen atoms in the molecular formula.