Final answer:
Polarizability is directly related to the size of the atom. In larger atoms, valence electrons are more easily distorted, leading to higher polarizability and larger dispersion forces.
Step-by-step explanation:
Polarizability is directly related to the size of the atom. In a larger atom, the valence electrons are on average farther from the nuclei than in a smaller atom, making them more easily distorted. This results in a higher polarizability and larger dispersion forces.