To solve for the problem above, note that the given compound is not charged which indicates that the sum of the oxidation numbers of atoms present is zero. The oxidation number of H is +1 and that of O is -2. Let x be the oxidation number of N and the generated equation is,
+1 + x + (-2)(2) = 0
From the equation the value of x is 3. Therefore, the oxidation number of N is 3.