When nitric acid (HNO3) reacts with iron(II) oxide (FeO), the products are iron(II) nitrate [Fe(NO3)2] and water (H2O). The chemical equation for this reaction is:

FeO + 2HNO3 → Fe(NO3)2 + H2O

In this reaction, the nitrate ion (NO3-) from nitric acid combines with the iron(II) ion (Fe2+) from iron(II) oxide to form iron(II) nitrate. The water is a byproduct of the reaction.