Final answer:
When nitrogen dioxide reacts with liquid water, it forms nitrous acid (HNO2).
Step-by-step explanation:
When nitrogen dioxide reacts with liquid water, it forms nitrous acid (HNO2). The balanced chemical equation for this reaction is:
NO2 (g) + H2O (l) → HNO2 (aq)
Nitrous acid is a weak acid that exists only in solution. It is unstable and readily disproportionates into nitric acid (HNO3) and nitric oxide (NO). Therefore, the compound produced when nitrogen dioxide reacts with liquid water is HNO2.