Draw the structures of the following oxoacids of phosphorus:
$(i)$ Orthophosphoric acid $(H_{3}PO_{4})$
$(ii)$ Pyrophosphoric acid $(H_{4}P_{2}O_{7})$
$(iii)$ Orthophosphorus acid $(H_{3}PO_{3})$
$(iv)$ Hypophosphorus acid $(H_{3}PO_{2})$
$(v)$ Cyclotrimetaphosphoric acid $((HPO_{3})_{3})$
$(vi)$ Polymetaphosphoric acid $((HPO_{3})_{n})$

(N/A) In oxoacids,phosphorus is tetrahedrally surrounded by other atoms. All these acids contain at least one $P=O$ bond and one $P-OH$ bond.
The oxoacids in which phosphorus has an oxidation state less than $+5$ contain either a $P-P$ bond or a $P-H$ bond in addition to $P-OH$ and $P=O$ bonds,but not both. The structures are provided in the reference image.