Assuming normal atmospheric pressure, at higher temperature, the
heat supplied to the system will disturb the intermolecular forces
of the molecule (breaking H-bonds among water molecules). Thus, the
molecules are farther apart, occupying larger volume.
The intermolecular forces in liquid is far stronger than those in
gaseous state. Stronger intermolecular forces -> stronger
attraction among molecules -> molecules are closer to one
another -> occupying smaller volume.
