Question

What is the difference in the oxidation number of Manganese (Mn) between \( \text{KMnO}_4 \) and \( \text{MnO}_2 \)?

• A. \(1\)
• B. \(2\)
• C. \(3\)
• D. \(4\)

Hint:

Always apply the rule that the sum of oxidation numbers in a neutral compound equals zero to determine unknown oxidation states.

Answer 1

The Correct Option is C

Concept: The oxidation number of an element in a compound is calculated using the rules:
• Oxygen usually has oxidation number \( -2 \)
• Potassium has oxidation number \( +1 \)
• The sum of oxidation numbers in a neutral compound is zero

Step 1: Find oxidation number of Mn in \( \text{KMnO}_4 \). Let the oxidation number of Mn be \(x\). \[ 1 + x + 4(-2) = 0 \] \[ 1 + x - 8 = 0 \] \[ x = +7 \] So Mn has oxidation number \(+7\) in \( \text{KMnO}_4 \).

Step 2: Find oxidation number of Mn in \( \text{MnO}_2 \). Let oxidation number of Mn be \(x\). \[ x + 2(-2) = 0 \] \[ x - 4 = 0 \] \[ x = +4 \]

Step 3: Find the difference. \[ 7 - 4 = 3 \] Thus the difference in oxidation number is \[ \boxed{3} \]