91影视

In a solution, the intermolecular force is defined as the attractive force between the molecules of solute and solvent which is determined from the relative strength within and between the solute and the solvent.

${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{14}}\left(\mathbf{l}\right){\mathbf{inC}}_{\mathbf{8}}{\mathbf{H}}_{\mathbf{18}}\left(\mathbf{l}\right)$: London Dispersion force

Both hexane and octane are nonpolar in nature, so the strongest intermolecular force between them is london Dispersion forces.

${\mathbf{H}}_{\mathbf{2}}\mathbf{C}\mathbf{=}\mathbf{O}\left(\mathbf{g}\right){\mathbf{inCH}}_{\mathbf{3}}\mathbf{OH}\left(\mathbf{l}\right)$: Hydrogen bonding

Hydrogen bonding is the strongest because of the polar formaldehyde molecule dissolves in polar solvent i.e., methanol.

${\mathbf{Br}}_{\mathbf{2}}{\mathbf{inCCl}}_{\mathbf{4}}\left(\mathbf{l}\right)$: London dispersion force

Both bromine and CCl₄ are nonpolar, evident from the Lewis structures of the Br₂ (linear) and CCl₄ (tetrahedral).

So, the only strongest intermolecular force here is london dispersion force.