From early studies, it can be found out that the presence of a hydrogen atom which is connected to the carbon-oxygen double bond in the aldehyde distinguishes it from a ketone. As ketones do not have that sort of hydrogen in them. Aldehydes are very easy to oxidize due to the presence of that hydrogen atom (that is, they are strong reducing agents). Whereas Ketones are more resistant to oxidation due to the lack of that particular hydrogen atom in them, and only very strong oxidizing agents such as potassium manganate (VII) solution (potassium permanganate solution) are able to oxidize them. This becomes possible to do but in a harmful manner, as the carbon-carbon bond is destroyed during this. Both aldehyde and ketone can be readily distinguished if the use of a powerful oxidizing agent is avoided in this. Also, Ketones are not easily oxidized by a variety of oxidizing agents, but aldehydes are. More detailed explanations and material on this topic can be found on the Vedantu website.