Final answer:
In HNO₂, the oxidation number of hydrogen is +1, the nitrogen is +3, and each oxygen is -2. The positive and negative charges balance out to maintain a neutral charge for the molecule.
Step-by-step explanation:
To find the oxidation number of each type of atom in nitrous acid, HNO₂, we'll apply the known rules for oxidation states. Generally, hydrogen has an oxidation number of +1, and oxygen has an oxidation number of -2. Since we have one hydrogen atom in HNO₂, it contributes +1. There are two oxygen atoms each with an oxidation number of -2, contributing a total of -4. Therefore, to balance the oxidation numbers in the molecule (which has to add up to zero because it is a neutral compound), the nitrogen must have an oxidation number that cancels out the +1 from hydrogen and the -4 from oxygen, giving nitrogen an oxidation number of +3 in HNO₂.
Summarizing:
- H (Hydrogen): +1
- N (Nitrogen): +3
- O (Oxygen): -2 (each)