Final answer:
Alkanals or aldehydes are not a typical direct product from the oxidation of alkenes using KMnO₄ and acid hydrolysis. Alkanoic acids and alkenones can be produced; however, the production of carbon dioxide would require further oxidation.
Step-by-step explanation:
The question asks which of the following cannot be obtained when alkenes are oxidised with potassium permanganate (KMnO₄) and then followed by acid hydrolysis among alkanoic acids, alkanals, alkanones, and carbon dioxide. In the process of oxidation with KMnO₄, alkenes can be converted into different compounds depending on their structure and the conditions of the reaction.
Alkenes can be converted into alkanoic acids and alkenones through oxidation. However, creation of alkanals is not typically associated with the oxidation of alkenes with KMnO₄ followed by acid hydrolysis. Alkanals or aldehydes are most often created through the oxidation of primary alcohols, where the -OH group is attached to a carbon bonded to no or one other carbon atom. And regarding carbon dioxide, it is not directly the product of oxidation of alkenes, but may be a side product through further oxidation of alkanones and alkanoic acids under certain conditions.
Learn more about Oxidation of Alkenes