The correct option for the oxidation state of manganese in potassium permanganate (KMnO₄) is **A. +7**. ### Step-by-Step Explanation: 1. **Understanding the Compound**: - Potassium permanganate is a chemical compound with the formula KMnO₄. It consists of potassium (K), manganese (Mn), and oxygen (O). 2. **Identifying Known Oxidation States**: - In compounds, certain elements have well-known oxidation states. - Potassium (K) is an alkali metal and always has an oxidation state of **+1**. - Oxygen (O) typically has an oxidation state of **-2** in most compounds. 3. **Setting Up the Equation**: - The overall charge of a neutral compound like KMnO₄ is zero. Therefore, we can set up an equation based on the oxidation states of the elements present. - Let the oxidation state of manganese (Mn) be represented as \( x \). - The compound contains one potassium atom, one manganese atom, and four oxygen atoms. The equation can be set up as follows: \[ \text{Total charge} = \text{Oxidation state of K} + \text{Oxidation state of Mn} + 4 \times \text{Oxidation state of O} \] \[ 0 = (+1) + x + 4(-2) \] 4. **Solving the Equation**: - Substitute the known values into the equation: \[ 0 = 1 + x - 8 \] - Simplifying this gives: \[ 0 = x - 7 \] - Therefore, solving for \( x \): \[ x = +7 \] 5. **Conclusion**: - The oxidation state of manganese in potassium permanganate (KMnO₄) is **+7**. ### Why Other Options Are Incorrect: - **B. +5**: - If manganese had an oxidation state of +5, the equation would not balance. Substituting +5 into the equation would yield: \[ 0 = 1 + 5 - 8 \implies 0 = -2 \quad (\text{not true}) \] - Therefore, +5 is not a valid oxidation state for manganese in this compound. - **C. +3**: - Similarly, if manganese had an oxidation state of +3, the equation would be: \[ 0 = 1 + 3 - 8 \implies 0 = -4 \quad (\text{not true}) \] - Thus, +3 is also incorrect. - **D. +2**: - If manganese had an oxidation state of +2, the equation would be: \[ 0 = 1 + 2 - 8 \implies 0 = -5 \quad (\text{not true}) \] - Therefore, +2 is not a valid oxidation state for manganese in this compound. ### Revision Summary: - The oxidation state of manganese in KMnO₄ is +7. - Potassium has an oxidation state of +1, and oxygen has an oxidation state of -2. - The overall charge of the compound must equal zero, leading to the equation: \( 0 = (+1) + x + 4(-2) \). - Solving the equation confirms that manganese's oxidation state is +7, making options B, C, and D incorrect.