PAsO4
The chemical formula of chromium(III) arsenate is CrAsO4.
The chemical formula BiAsO4 corresponds to the compound Bismuth arsenate.
Phosphorus(III) oxide has the formula P2O3 but it exists as the molecule of P4O6
BiAsO4
PCl3 is the formula. This is the compound we know as phosphorus trichloride.
The chemical formula for titanium (III) phosphide is Ti3P. It consists of three titanium atoms bonded to one phosphorus atom.
Phosphorus (III) oxide: P4O6
FeAsO3 is the chemical formula of the iron (III) arsenite.
Phosphorus tri-iodide refers to Phosphorus(III) Iodide, with formula PI3
That would be chromium(II) sulfate, but really, chromium mostly exists as Cr(III) or Cr(VI), which would change the formula.
The chemical formula for chromium(III) phosphide is CrP. In this compound, chromium has a +3 charge, while phosphorus has a -3 charge.
The chemical formula of iron(III) and selenium is Fe2Se3 - iron(III) selenide.