What effect does branching have on boiling points of hydrocarbons?

Branching in hydrocarbons generally decreases boiling points, which is due to the way molecular structure influences intermolecular forces. In a straight-chain hydrocarbon, the molecules can pack closely together, allowing for stronger van der Waals forces, also known as London dispersion forces. This close packing leads to higher boiling points.

However, when a hydrocarbon is branched, its shape becomes more compact. The branched structure prevents the molecules from coming together as closely as their straight-chain counterparts. As a result, the strength of the intermolecular forces decreases, leading to lower boiling points. This is a key concept in understanding the physical properties of alkanes and other hydrocarbons.

In summary, the correct answer accurately reflects how the presence of branching affects the boiling points of hydrocarbons; as branching increases, boiling points tend to decrease due to reduced surface area available for intermolecular interactions.