What is the highest oxidation state possessed by phosphorus in it's oxyacids?
What is the highest oxidation state possessed by phosphorus in it's oxyacids?
$+6$
$+4$
$+3$
$+5$
Solution
$+5$
$+5$ is the highest oxidation state possessed by phosphorus in it's oxyacids. In oxoacids phosphorus is tetrahedrally surrounded by other atoms. All these acid contains at least one $\mathrm{P}=$ O bond and one $\mathrm{P}-\mathrm{OH}$ bond. The oxoacids in which phosphorus has maximum oxidation state $(+5)$ is orthophosphoric $\left(\mathrm{H}_{3} \mathrm{PO}_{4}\right)$, pyrophosphoric $\left(\mathrm{H}_{4} \mathrm{P}_{2} \mathrm{O}_{7}\right)$ and metaphosphoric $\left(\mathrm{HPO}_{3}\right)_{n}$.
