Structural formula for butene?

• A. CH2 CH CH2 CH3
• B. CH3-CH2-CH2-CH3
• C. CH2 CH CH3 CH3
• D. CH3 CH CH2 CH3

Answer: (A)

Butene is an alkene with four carbon atoms, so its structural formula must include a C=C double bond and four carbons in the chain.

The best representation shows a double bond between the first two carbons and continues with two more carbons, giving CH2=CH-CH2-CH3. This matches but-1-ene, the four-carbon chain with a double bond.

The other options either show only single bonds (no C=C) or mis arrange the carbon skeleton, which would correspond to alkanes like butane or other connectivity that does not depict butene.