Question

What is the oxidation state of Phosphorus in \( H_3PO_4 \)?

• A. \(+3\)
• B. \(+5\)
• C. \(+1\)
• D. \(+7\)

Hint:

For neutral molecules, the sum of oxidation numbers is zero. Use common values such as \(H = +1\) and \(O = -2\) to easily determine the unknown oxidation state.

Answer 1

The Correct Option is B

Concept: The sum of oxidation states of all atoms in a neutral molecule is zero. Standard oxidation numbers: - Hydrogen \(= +1\) - Oxygen \(= -2\)
Step 1: {Assign oxidation numbers.} Let the oxidation state of phosphorus be \(x\). For \(H_3PO_4\): Hydrogen contribution: \[ 3 \times (+1) = +3 \] Oxygen contribution: \[ 4 \times (-2) = -8 \]
Step 2: {Apply the oxidation state rule.} \[ x + 3 - 8 = 0 \] \[ x - 5 = 0 \] \[ x = +5 \]