Which option shows the displayed formula for butane?

Which option shows the displayed formula for butane?

• A. CH3-CH2-CH2-CH3
• B. CH3-CH2-CH2-CH2-CH3
• C. C4H10
• D. CH4

Answer: (A)

Understanding how butane is represented in a displayed (structural) formula helps you see not just what atoms are present, but how they are connected. Butane has four carbon atoms arranged in a straight chain, and each carbon forms four bonds in total with either carbon or hydrogen. In a displayed formula, the bonds between carbons are shown explicitly and the hydrogens are written to satisfy carbon’s valence: the ends are CH3 (three hydrogens on each terminal carbon) and the two middle carbons are CH2 (two hydrogens each). This is exactly CH3-CH2-CH2-CH3, which shows four carbons in a row with the appropriate hydrogens and single bonds. The other options don’t match this display: one shows five carbons (pentane), another is the molecular formula C4H10 without the bond structure, and the last is methane, CH4.

Understanding how butane is represented in a displayed (structural) formula helps you see not just what atoms are present, but how they are connected. Butane has four carbon atoms arranged in a straight chain, and each carbon forms four bonds in total with either carbon or hydrogen. In a displayed formula, the bonds between carbons are shown explicitly and the hydrogens are written to satisfy carbon’s valence: the ends are CH3 (three hydrogens on each terminal carbon) and the two middle carbons are CH2 (two hydrogens each). This is exactly CH3-CH2-CH2-CH3, which shows four carbons in a row with the appropriate hydrogens and single bonds. The other options don’t match this display: one shows five carbons (pentane), another is the molecular formula C4H10 without the bond structure, and the last is methane, CH4.