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EEJ MAIN Chemistry QUESTION #7151
Question 1
In which of the following pairs do both phosphorus atoms exhibit a formal oxidation state of $+3$?
  • Pyrophosphorous and hypophosphoric acids
  • Orthophosphorous and hypophosphoric acids
  • Pyrophosphorous and pyrophosphoric acids
  • Orthophosphorous and pyrophosphorous acids✔️
Correct Answer Explanation
The oxidation states of phosphorus are as follows:
  • Orthophosphorous acid ($H_{3}PO_{3}$): $+3$
  • Pyrophosphorous acid ($H_{4}P_{2}O_{5}$): $+3$
  • Hypophosphoric acid ($H_{4}P_{2}O_{6}$): $+4$
  • Pyrophosphoric acid ($H_{4}P_{2}O_{7}$): $+5$
Therefore, the pair where both are $+3$ is Orthophosphorous and pyrophosphorous acids.