What is the minimum number of carbon atoms required for an aliphatic, non-cyclic ketone to exhibit metamerism?

Step-by-step solution

Metamerism arises due to different alkyl chains on either side of a polyvalent functional group. For ketones, the functional group is the carbonyl group ( - CO - ), which is divalent. Let us check the homologous series of aliphatic ketones: With 3 carbon atoms: CH ₃- CO - CH ₃ (Propanone). No other arrangement of alkyl groups around the carbonyl carbon is possible. With 4 carbon atoms: CH ₃- CO - CH ₂ CH ₃ (Butan-2-one). No other arrangement is possible. With 5 carbon atoms: The alkyl groups can be a methyl and a p