The oxidation state of nitrogen in HNO3 nitric acid can be determined by assigning oxidation numbers to each element in the compound and then solving for the unknown oxidation state of nitrogen.1. Hydrogen H has an oxidation state of +1.2. Oxygen O has an oxidation state of -2.Now, set up an equation using the oxidation numbers and the chemical formula HNO3: +1 + x + 3 -2 = 0Solve for x the oxidation state of nitrogen :x - 6 = -1x = +5So, the oxidation state of nitrogen in HNO3 is +5.