Final answer:
The intermolecular force present in a pure sample of water (H2O) is hydrogen bonding.
Step-by-step explanation:
In a pure sample of H2O (water), the intermolecular force present is hydrogen bonding. Hydrogen bonding occurs when a hydrogen atom is bonded to one of the highly electronegative atoms like oxygen, nitrogen, or fluorine. In water, the hydrogen atoms are bonded to the oxygen atom, resulting in strong dipole-dipole interactions.