Which intermolecular force arises from temporary dipoles due to fluctuating electron distribution?

• A. Hydrogen bonding
• B. London dispersion forces
• C. Dipole
• D. Solvent

Answer: (B)

Temporary fluctuations in electron distribution create instantaneous dipoles in atoms or nonpolar molecules. These momentary dipoles induce neighboring dipoles, producing a weak attraction called London dispersion forces. They arise from the random motion of electrons and exist in all substances, becoming more significant as molecular size and electron count increase (larger, more polarizable clouds lead to stronger dispersion). Hydrogen bonding involves specific strong interactions with hydrogen bonded to F, O, or N and is not about temporary dipoles. A dipole refers to a permanent separation of charge, not a fleeting one. Solvent is simply a substance, not a type of intermolecular force. So the described force is London dispersion forces.