Final answer:
The oxidation number of Mn in KMnO₄ is determined by accounting for the known oxidation states of other elements in the compound and the fact that the overall charge of the compound is neutral. Potassium has an oxidation number of +1, and oxygen has an oxidation number of -2. Therefore, Mn must have an oxidation number of +7 to balance the charges in KMnO₄.
Step-by-step explanation:
To find the oxidation number of Mn in KMnO₄, we need to consider the oxidation numbers of the other atoms in the compound. Oxygen has a consistent oxidation number of -2. In potassium permanganate, there are four oxygen atoms, contributing a total of -8 to the oxidation state.
Since the compound is neutral, the sum of the oxidation numbers must equal zero. Potassium (K) has an oxidation state of +1. So, the equation to find the oxidation state of manganese (Mn) looks like this: +1 (for K) + x (for Mn) + (-2 × 4) (for O) = 0. Simplifying this equation gives us the oxidation number for Mn: +1 + x - 8 = 0, which simplifies to x = +7.
Therefore, the correct answer is +7, and the oxidation number of Mn in KMnO₄ is +7.