Which functional group is present in the molecule named $2-\mathrm{ethyl}-1-\mathrm{hexene}$?

• A. $\mathrm{Alkene}$
• B. $\mathrm{Alcohol}$
• C. $\mathrm{Aldehyde}$
• D. $\mathrm{Alkyne}$

Answer: (A)

Verified step by step guidance

1. Identify the root name of the compound, which is 'hexene'. The suffix '-ene' indicates the presence of a carbon-carbon double bond, characteristic of an alkene functional group.
2. Recognize the numbering in the name '2-ethyl-1-hexene'. The '1-hexene' part means the double bond starts at carbon 1 of the hexene chain.
3. Note the substituent '2-ethyl', which is an ethyl group attached to carbon 2 of the main chain. This does not change the functional group but provides information about branching.
4. Recall the definitions of the functional groups listed: Alcohols contain an -OH group, Aldehydes have a -CHO group, Alkynes contain a carbon-carbon triple bond, and Alkenes contain a carbon-carbon double bond.
5. Since the name includes 'hexene' indicating a double bond and no other functional group suffixes or prefixes are present, conclude that the functional group in this molecule is an alkene.