The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. what is this attraction called?

This attraction called hydrogen bond.

Explanation:

We know that in water molecule the unequal sharing of electron between oxygen and hydrogen atoms gives a partial negative charge to oxygen atom and partial positive charge to hydrogen atom and this gives rise to an attraction between water molecules, which is called hydrogen bond. This force of attraction is weaker than an ionic bond and covalent bond but stronger than vander waals forces.

b) mutualism

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