What are the redox reactions involving carbonyls?
Carbonyls are aldehydes and ketones, both can be a product of an alcohol's oxidation reaction. A common reagent for that is potassium dichromate and sulphuric acid (the dichromate ion is reduced to a Cr3+ and changes its colour to green). An aldehyde can be produced from the oxidation of a primary alcohol (the hydroxil group is conected to a primary carbon atom), and a ketone from a secondary alcohol. The carbonyls can both be reduced back to alcohol for example by sodium tetrahydroborate.
One large difference between aldehydes and ketones is that only former one can be oxydated further. Therefore there are two important reagents that can be used when distinguishing between an aldehyde and a ketone: the Tollens reagent and the Fehling-solution. These reactions can both produce a carboxylic acid.
If explaining, I would also draw the molecules and write down the general equations for the reactions and some examples.
