p-Block Elements: JEE Main Chemistry Question with Solution
The oxidation state of phosphorus in hypophosphoric acid is +
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Hint 1 of 2
What is the correct chemical formula of hypophosphoric acid?
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Correct answer
The oxidation state of phosphorus in hypophosphoric acid (H4P2O6) is +4.
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Solution
StepWorking
01given
Compound: Hypophosphoric acid.
02find
Oxidation state of phosphorus (P) in hypophosphoric acid.
03visualise
Recall the molecular formula of hypophosphoric acid: H4P2O6. Structurally, it contains a direct P−P bond: (HO)2P(=O)−P(=O)(OH)2.
04strategise
Assign standard oxidation states: H=+1, O=−2. Let the oxidation state of phosphorus be x. Since the molecule is neutral, the sum of all oxidation numbers must equal zero: 4(+1)+2(x)+6(−2)=0.
05execute
Solving for x:
4+2x−12=0⟹2x=8⟹x=+4
✓verify
Using the structure: each P is bonded to two −OH groups (contributing +1 each), one =O (contributing +2), and one identical P atom through a P−P single bond (contributing 0). Net oxidation state per P=1+1+2+0=+4. Consistent.
Hints that build this answer step by step
What is the correct chemical formula of hypophosphoric acid?
H4P2O6
Using standard oxidation states (H=+1 and O=−2), what is the oxidation state of phosphorus (x) in H4P2O6?
What is the difference between hypophosphoric acid and hypophosphorous acid?
Hypophosphorous acid is H3PO2 (also called phosphinic acid) where P is in the +1 oxidation state. Hypophosphoric acid is H4P2O6 where P is in the +4 oxidation state.