Final answer:
Nitric acid (HNO3) is a pure substance that is a highly corrosive mineral acid and a strong oxidizing agent. It is typically a colorless liquid, but it can appear yellow or brown due to the formation of nitrogen dioxide (NO2) as the acid decomposes.
Step-by-step explanation:
Nitric acid (HNO3) is a pure substance. It is a highly corrosive mineral acid and a strong oxidizing agent. It is typically a colorless liquid, but it can appear yellow or brown due to the formation of nitrogen dioxide (NO2) as the acid decomposes.