Final answer:
An isoelectric molecule, with its net charge being zero, doesn't affect the London dispersion forces directly, as these forces are a result of temporary dipoles due to electron distribution fluctuations, and generally increase with molecular size and electron count.
Step-by-step explanation:
When a molecule is isoelectric, it has reached a state where its net charge is zero because the number of positive and negative charges are balanced, usually at a specific pH level. This condition influences the strength of the London dispersion forces within the molecule. Since London dispersion forces arise due to the formation of temporary dipoles from fluctuations in electron distribution, an isoelectric molecule with no permanent dipole moment will mainly rely on instantaneous dipole-induced dipole interactions to establish these forces. Typically, the strength of London dispersion forces increases with the size and number of electrons in a molecule, not directly with the isoelectric property of a molecule.