Question

The pair in which phosphorous atoms have a formal oxidation state of +3 is ______.

Options

• orthophosphorous and pyrophosphorous acids

• pyrophosphorous and hypophosphoric acids

• orthophosphorous and hypophosphoric acids

• pyrophosphorous and pyrophosphoric acids

Answer 1

The pair in which phosphorous atoms have a formal oxidation state of +3 is orthophosphorous and pyrophosphorous acids.

Explanation:

In orthophosphorous acid (H₃PO₃) and pyrophosphorous acid (H₄P₂O₅), the phosphorus atoms have a formal oxidation state of +3. This is because both acids contain P-H bonds and fewer P-O bonds compared to other phosphorus oxoacids, resulting in the +3 oxidation state. Other acids like hypophosphoric and pyrophosphoric acids have higher oxidation states (for example, +4 in hypophosphoric and +5 in pyrophosphoric acid) due to more P-O bonding and different structural arrangements.