In the compound KMnO_4, what is the oxidation number of the manganese (Mn) atom?

• A. +7
• B. +2
• C. +4
• D. +3

Answer: (A)

Verified step by step guidance

1. Identify the known oxidation states of the other elements in the compound KMnO_4. Potassium (K) is an alkali metal and typically has an oxidation number of +1.
2. Recognize that oxygen (O) almost always has an oxidation number of -2 in compounds, except in peroxides or when bonded to fluorine. Here, oxygen is in the -2 state.
3. Write the equation for the sum of oxidation numbers in the compound, which must equal zero because KMnO_4 is neutral: \$1 + x + 4(-2) = 0\(, where \)x$ is the oxidation number of manganese (Mn).
4. Simplify the equation: \$1 + x - 8 = 0\(, which reduces to \)x - 7 = 0$.
5. Solve for \(x\) to find the oxidation number of Mn: \(x = +7\).