Final answer:
The oxidation state of nitrogen in Ba(NO3)2 is +5, derived from calculating the total charge of the nitrate ion and knowing the oxidation states of barium and oxygen. The correct answer is option D. +5.
Step-by-step explanation:
The oxidation state of nitrogen (N) in Ba(NO3)2 can be calculated by using the rules for assigning oxidation states. Barium (Ba) as an alkaline earth metal has an oxidation state of +2. The nitrate ion (NO3-) has a charge of -1, and since there are two nitrate ions, the overall charge they contribute is -2. The sum of the oxidation states in a compound must equal the overall charge of the compound, which for Ba(NO3)2 is zero.
Each oxygen in the nitrate ion has an oxidation state of -2, hence for one NO3- ion:
x + 3(-2) = -1
where x is the oxidation number of the N atom and the -1 represents the charge on the species. Solving for x:
x + (-6) = -1
x = +5
Therefore, the correct answer is option D. +5