The name trisodium phosphate is incorrect for the compound Na3PO4 because ____(A) this compound should be called trisodium monophosphate.(B) the sodium has a positive 3 charge.(C) you cannot use a prefix for the first element in a molecular compound.(D) you cannot use a prefix for the first element of an ionic compound.

The name of the cation is written first and the the name of the anion is written after the name of the cation separated by single space.
The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.
In case of transition metals, the oxidation state are written in roman numerals in bracket in front of positive ions.

Hence, given ionic compound:-

[tex]Na_3PO_4[/tex] is formed of cation, [tex]Na^+[/tex] and anion,[tex]PO_4^{3-}[/tex]

Thus, the name must be sodium phosphate.

The name is incorrect because - (D) you cannot use a prefix for the first element of an ionic compound.