The IUPAC names of the compounds CH₃COOH and CH₂=CH₂ are respectively;

Explanation

CH₃COOH contains two carbon atoms, with a -COOH (carboxyl) group at the end. In IUPAC naming, a two-carbon chain is “ethan-” and the -COOH group gives the suffix “-oic acid.” So CH₃COOH is ethanoic acid. It is also commonly known as acetic acid, the main component of vinegar.

CH₂=CH₂ also has two carbon atoms, connected by a carbon-carbon double bond (C=C). The prefix for two carbons is “eth-” and the double bond gives the suffix “-ene.” So CH₂=CH₂ is ethene. It is the simplest alkene and is widely used in making polyethylene (polythene).

Ethanol (C₂H₅OH) has an -OH group, not a -COOH group, so it is an alcohol, not an acid. Ethyne (C₂H₂) has a carbon-carbon triple bond (C≡C), not a double bond. The key is matching the correct functional group to the correct IUPAC suffix: -oic acid for carboxyl groups, -ene for double bonds, -ol for hydroxyl groups, and -yne for triple bonds.