Here's a breakdown:

* Nitrogen dioxide (NO2), a major component of NOx, reacts with water (H2O) to form nitric acid (HNO3) and nitrous acid (HNO2).

* Nitric acid (HNO3) is a strong acid that contributes to acid rain.

* Nitrous acid (HNO2) is a weaker acid that also contributes to acid rain but is less stable than nitric acid and can further decompose.

This reaction is important because it's how nitrogen oxides contribute to the formation of acid rain, which can have detrimental effects on ecosystems and infrastructure.