(N/A) Aldehydes differ from ketones in their oxidation reactions. The following reactions are used to identify aldehydes and ketones.
$(a)$ Oxidation by strong oxidizing agents:
$(i)$ Aldehyde compounds: Aldehydes are easily oxidized to carboxylic acids on treatment with common oxidizing agents like nitric acid $(HNO_3)$,potassium permanganate $(KMnO_4)$,potassium dichromate $(K_2Cr_2O_7)$,etc.
$R-CHO \xrightarrow{(O) HNO_3 / KMnO_4 / K_2Cr_2O_7} RCOOH$
In this reaction,the number of carbon atoms remains constant. The $C-H$ bond is converted to a $C-OH$ bond.
$(ii)$ Ketone compounds: Ketones are generally oxidized under vigorous conditions,i.e.,using strong oxidizing agents at elevated temperatures. Their oxidation involves carbon-carbon bond cleavage to afford a mixture of carboxylic acids having fewer carbon atoms than the parent ketone.
For example,the oxidation of an unsymmetrical ketone $R-CH_2-CO-CH_2-R'$ leads to cleavage at different positions:
$R-CH_2-CO-CH_2-R' \xrightarrow{(O) KMnO_4/HNO_3/K_2Cr_2O_7, \Delta} R-COOH + R'-CH_2COOH + R-CH_2COOH + R'-COOH$
This results in a mixture of products due to cleavage of both $C_1-C_2$ and $C_2-C_3$ bonds.