Within a single molecule of water, two hydrogen bonds are bonded to a single oxygen atom when there are multiple water molecules, the partial negative charge at one end of a water molecule attracted to the partial ositive charge of another water molecule forms

covalent bonding, hydrogen bonding

Explanation:

The molecular formula of water is in which the two hydrogen atoms are connected to the oxygen atom via covalent bonds which means that the electrons are shared in the bond.

Hydrogen bonding is a special type of the dipole-dipole interaction and it occurs between hydrogen atom that is bonded to highly electronegative atom which is either fluorine, oxygen or nitrogen atom.

Partially positive end of the hydrogen atom is attracted to partially negative end of these atoms which is present in another molecule. It is strong force of attraction between the molecules.

Thus, when multiple water molecules are there, there are connected by hydrogen bonding.