2- pentanone and 3- pentanone are

Nature of alkyl groups and the number of carbon atoms in the alkyl groups attached to a bivalent functional group are different. They are metamers.CH3-CH2-CH2-CO-CH32- pentanone;      n- propyl                   Methyl CH3-CH2-CO-CH2-CH33- pentanone;     Ethyl                         Ethyl