How are London dispersion forces between molecules produced?
Due to the movement of electrons...
Since electrons are always moving rapidly everywhere in an atom, at some point, there'll be a time where all of the electrons are stuck in one region, and the other molecule's electrons are stuck on the opposite region, forming temporary dipoles, and therefore attracting each other to the process.
Note that this is a form of very weak van der Waals forces, as opposed to hydrogen bonding and such.
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