Question:medium

Find the oxidation state of Phosphorus in \( H_3PO_4 \) and \( H_3PO_3 \).

Show Hint

Always assign known oxidation states first (H = +1, O = -2), then solve for the unknown element.
Updated On: Apr 15, 2026
  • \(+5\) and \(+3\)
  • \(+3\) and \(+5\)
  • \(+4\) and \(+3\)
  • \(+5\) and \(+4\)
Show Solution

The Correct Option is A

Solution and Explanation

Step 1: Understanding the Question:
Oxidation state reflects the degree of oxidation of an atom in a compound. We calculate it by balancing the known charges of Hydrogen and Oxygen.
Step 2: Key Formula or Approach:
Rule: Sum of oxidation states in a neutral molecule \( = 0 \).
Standard values: \( H = +1 \), \( O = -2 \).
Step 3: Detailed Explanation:
1. For \( H_3PO_4 \) (Phosphoric acid):
\[ 3(+1) + x + 4(-2) = 0 \]
\[ 3 + x - 8 = 0 \implies x = +5 \]
2. For \( H_3PO_3 \) (Phosphorous acid):
\[ 3(+1) + x + 3(-2) = 0 \]
\[ 3 + x - 6 = 0 \implies x = +3 \]
Step 4: Final Answer:
The oxidation states are \( +5 \) and \( +3 \) respectively.
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