Answer:
Branching of an alkane chain decreases its boiling point.
Explanation:
As branching in an alkane increases, the molecule becomes more compact and nearly spherical.
This reduces the surface area of contact between molecules.
Due to smaller surface area, the van der Waals forces (intermolecular attractions) between molecules become weaker.
Weaker intermolecular forces require less energy to separate the molecules, resulting in a lower boiling point.
Example:
For isomeric alkanes:
n-butane > isobutane (2-methylpropane)
n-pentane > isopentane > neopentane
Thus, more branching → lower boiling point.