Which of the following statements is NOT valid for oxoacids of phosphorus?

1. Correct: The basic structural unit of P-oxoacids involves $\text{P}=\text{O}$ and $\text{P}-\text{OH}$.2. Correct: Triple superphosphate is produced by the action of ${\text{H}}_3{\text{PO}}_4$ on phosphate rock.3. Incorrect: Hypophosphorous acid (${\text{H}}_3{\text{PO}}_2$) has one $\text{P}-\text{OH}$ group and two $\text{P}-\text{H}$ bonds. Since only the hydrogen in $\text{P}-\text{OH}$ is ionizable, it is a monoprotic acid.4. Correct: Phosphorus is $s{p}^3$ hybridized in these acids.