Final answer:
The oxidation number of N in K₃Fe(CN)₆ is -3, which is determined by considering the charges of the other atoms and ions in the compound and the overall neutrality of the compound.
Step-by-step explanation:
The oxidation number of N in K₃Fe(CN)₆ can be determined by considering the charges within the compound. Potassium (K) has an oxidation number of +1, and there are three potassium ions, contributing a total charge of +3. The compound is neutral, so the sum of oxidation numbers must be zero. Cyanide (CN) has an overall -1 charge. Since there are six cyanide ions, this contributes a charge of -6. The oxidation state of iron (Fe) in this complex is typically +3 (Fe₃⁺), which is determined by the color and magnetic properties of the compound. The nitrogen (N) within the cyanide ion must balance the -1 charge of the ion considering that carbon (C) has an oxidation number of +2. Hence, the nitrogen would have an oxidation number of -3 to result in CN-1. Therefore, the correct answer is e) −3.