Which of the following alkenes is the most stable?

• A. $\mathrm{CH}=\mathrm{CH}{\mathrm{CH}}_3$ (propene)
• B. ${\mathrm{CH}}_2=\mathrm{CH}{\mathrm{CH}}_3$ (1-propene)
• C. ${\mathrm{CH}}_2={\mathrm{CH}}_2$ (ethylene)
• D. ${\mathrm{CH}}_3\mathrm{CH}=\mathrm{CH}{\mathrm{CH}}_3$ (trans-2-butene)

Answer: (D)

Verified step by step guidance

1. Identify the structure of each alkene given in the problem, noting the position of the double bond and the substituents attached to the alkene carbons.
2. Recall that alkene stability is influenced by the degree of alkyl substitution on the double bond: more substituted alkenes are generally more stable due to hyperconjugation and inductive effects.
3. Consider the difference between cis and trans isomers for alkenes with the same substitution pattern; trans isomers are typically more stable than cis isomers because of reduced steric strain.
4. Compare the given alkenes by counting the number of alkyl groups attached to the double-bonded carbons and identifying if they are cis or trans configurations.
5. Conclude that the most stable alkene is the one with the highest substitution and trans configuration, which maximizes hyperconjugation and minimizes steric hindrance.