Which is the structural formula for butane?

Which is the structural formula for butane?

• A. CH4
• B. CH3 CH3
• C. CH3 CH2 CH3
• D. CH3 CH2 CH2 CH3

Answer: (D)

Butane is a straight-chain alkane with four carbon atoms. In its structural formula, the four carbons are connected in a row, with the end carbons carrying three hydrogens (CH3) and the inner carbons carrying two hydrogens (CH2). Put together, that gives CH3-CH2-CH2-CH3 (often written CH3CH2CH2CH3). This shows four carbons in a continuous chain, which is why it represents butane. The other options reflect fewer carbon atoms: CH4 is methane (one carbon), CH3 CH3 would be two methyl groups (ethane would be CH3-CH3 but written separated isn’t a single chain), and CH3-CH2-CH3 is propane (three carbons).

Butane is a straight-chain alkane with four carbon atoms. In its structural formula, the four carbons are connected in a row, with the end carbons carrying three hydrogens (CH3) and the inner carbons carrying two hydrogens (CH2). Put together, that gives CH3-CH2-CH2-CH3 (often written CH3CH2CH2CH3). This shows four carbons in a continuous chain, which is why it represents butane. The other options reflect fewer carbon atoms: CH4 is methane (one carbon), CH3 CH3 would be two methyl groups (ethane would be CH3-CH3 but written separated isn’t a single chain), and CH3-CH2-CH3 is propane (three carbons).