CH₂=CHCH₃: This is an alkene compound, as it contains a double bond (C=C).
CH₃-CH₂-COOH: This is a carboxylic acid because it contains the –COOH (carboxyl) group.
CH₃-OH: This is an alcohol because it contains the –OH (hydroxyl) group.
CH₃-CH₂-O-CH₃: This is an ether, as it contains the –O– (oxygen) linkage between two alkyl groups.