Question

which step in naming unsaturated hydrocarbons is used for alkenes but not alkynes? identify the longest chain of carbon atoms. examine the multiple bond for cis - and trans - isomers. number the chain of carbons, starting with the end nearest the multiple bond. add a number prefix indicating the first carbon atom in the multiple bond.

Explanation:

Alkenes have double - bonds which can exhibit cis - and trans - isomerism. Alkynes have triple - bonds and do not have this type of isomerism. Identifying cis - and trans - isomers is a naming step specific to alkenes.

Answer:

Examine the multiple bond for cis - and trans - isomers