Nitric acid is an oxidising agent and reacts with PbO but it does not react with `PbO_(2)`. Explain why ?

Explanation

(i) Nitric acid in an oxidising agent. It oxidises an element from lower oxidation state to higher oxidation state. In PbO, lead is in lower oxidation state of `+2. HNO_3` oxidises from `Pb^(2+)` to `Pb^(4+)`.
`PbO+2HNO_(3)toPb(NO_3)_2+H_2O`
(ii) In `PbO_2` ,lead is in `+4` oxidation state and cannot be oxidised further. Therefore no reaction takes place.