Question

question
which of the following is an alkene?
select the correct answer below:
○ ch₃ - ch₂ - ch(ch₃) - ch₃
○ ch₃ - c(ch₃)₂ - c(ch₃)₂ - ch₃
○ ch₂ = c(ch₃) - ch₂ - ch₃
○ ch ≡ c - ch₂ - ch = ch₃

Explanation:

Step1: Recall alkene definition

Alkenes have carbon - carbon double bonds (C = C).

Step2: Analyze each option

1. CH₃−CH₂−CH(CH₃)−CH₃ has only single bonds, it's an alkane.
2. CH₃−C(CH₃)₂−C(CH₃)₂−CH₃ has only single bonds, it's an alkane.
3. CH₂=C(CH₃)−CH₂−CH₃ has a carbon - carbon double bond, so it's an alkene.
4. CH≡C−CH₂−CH=CH₃ has a carbon - carbon triple bond (C≡C) and a double bond, but the presence of the triple bond makes it an alkyne - alkene hybrid, not just an alkene.

Answer:

CH₂=C(CH₃)−CH₂−CH₃