Actually Nitric oxide reacts with both PbO and PbO₂

Pb has an EC as: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p². The outermost orbital can give 4 electrons, so can exhibit multiple oxidation states. In PbO the Oxidation number is +2 and that in PbO₂ is +4. As seen by the EC, Pb can only donate 4 outermost electrons to gain an oxidation state of +4. Oxidation by nitric acid of PbO takes place as:

Oxidation of PbO₂ takes place as:

As seen by the reactions of PbO₂ we require drastic conditions and excess of nitric acid in order for the reaction to occur spontaneously. Also if we consider whether HNO₃ can oxidize PbO or not, under non – reactive conditions, can be discussed. As PbO has ON as +2, it can undergo oxidation by giving two electrons to nitric acid to attain Pb⁴⁺ state. As there are no more valence electrons in the outer most EC of Pb it won’t undergo oxidation further, thus nitric acid cannot oxidize PbO₂. Also the ionization energy for Pb to give 4 electrons is high as compared to Sn which shows ON +4. Thus oxidation is not possible for a Pb⁴⁺ ionic state.