Final answer:
The compound in which nitrogen has an oxidation number of +4 is N₂O₅ (option b).
Step-by-step explanation:
The compound in which nitrogen has an oxidation number of +4 is N₂O₅ (option b).
Oxidation number is the charge that an atom would have if electrons were transferred completely. In N₂O₅, nitrogen is bonded to two oxygen atoms. Since oxygen has an oxidation number of -2, the sum of the oxidation numbers in the compound must be zero. Let the oxidation number of nitrogen be x. The equation becomes: 2(+5) + x = 0. Solving for x, we get: x = -10 + 4 = +4.
Therefore, in N₂O₅, nitrogen has an oxidation number of +4.