How do you represent a branched alkane in a structural formula?

To represent a branched alkane in a structural formula, the correct approach is using a tree-like structure. This method effectively illustrates the central carbon chain, often referred to as the parent chain, along with any substituents or side chains that branch off from it.

In a branched alkane, the main carbon chain is shown as a linear backbone, while branches are depicted as smaller chains or groups extending from the main chain. This representation clearly communicates the connectivity of the carbon atoms and helps in visualizing the spatial arrangement of the molecule.

The other options do not adequately convey the complexities involved in depicting branched alkanes. Lines with dots may represent different types of bonding or lone pairs in other contexts but lack the clarity needed for branching structures. Circular diagrams can imply cyclic compounds rather than open chain alkanes. Straight lines only would not show branching and would imply a linear chain, which fails to represent the branched nature of the molecule. Thus, a tree-like structure is the most effective way to depict branched alkanes in structural formulas.