This attractive force results from charge-charge interactions between molecules due to transient uneven distributions of electrons. The positive and negative charges attract.
Branched alkanes have a lower boiling point than their corresponding unbranched isomer.
Branching produces less efficient packing and thus weakens the intermolecular interactions. Since C-H groups are not hydrogen bond donors, alkanes disrupt the hydrogen bonding network of water. Like dissolves like. Alkanes are very soluble in other organic solvents. The longest continuous carbon is the parent compound.