Answer:
Hydrogen bonding.
Step-by-step explanation:
Hydrogen bonding is basically the force which holds the molecules of water together. It is an extremely strong force and is responsible for higher boiling point of water. Hydrogen bonding occurs due to electronegativity difference between Oxygen and Hydrogen atoms. Hydrogen atom develops partial negative charge while Oxygen develops partial positive charge. Therefore, Oxygen atom of one molecule attracts the hydrogen of other molecule and this goes one. This way extremely strong bonding develops that holds water molecules together.
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