Aldehydes are readily oxidized to yield carboxylic acid, but ketones are generally inert toward oxidation. The difference is a consequence of structure: Aldehydes have a -CHO proton that can be abstracted during oxidation, but ketones do not.
Many oxidizing agents, including KMnO4 and hot HNO3 , Convert aldehydes into carboxylic acid, but CrO3 in aqueous acid is a more common choice in the laboratory. The oxidation occurs rapidly at room temperature and results in good yields.