Which ion is represented by the formula PO3(3-)?

The ion represented by the formula PO3(3-) is phosphite. This can be understood by examining the composition of the ion. The chemical formula PO3 indicates that it consists of one phosphorus (P) atom and three oxygen (O) atoms.

In chemistry, when discussing common phosphorus oxoanions, two important ions are phosphate and phosphite, which can often lead to confusion. Phosphate is represented by the formula PO4(3-), which contains four oxygen atoms and carries the same 3- charge as phosphite. In contrast, the phosphite ion, which has three oxygen atoms, is specifically denoted by PO3(3-), illustrating the difference in the number of oxygen atoms between the two ions.

The oxidation state of phosphorus in phosphite is +3, as phosphorus is bonded to three oxygen atoms. This characterization is based on the fundamental definitions of these ions within inorganic chemistry. Other options listed, such as arsenite and bromate, refer to entirely different ions associated with arsenic and bromine, respectively, and would not match the given formula. Thus, the accurate identification of the compound PO3(3-) leads directly to the conclusion that it is indeed the phosphite ion.