Explain how Coulomb's law can help you understand why some interparticle forces are stronger than others.

Coulombs equation involves distance and the distance from one radius to the next allows us to predict certain characteristics such as pull and attraction. For example, you would expect, a higher charge on the ion and a higher dipole moment causes a larger force. This is due to the magnitude which is the distance between these two and effectively that is how Columbus law comes into play.

the answer for sodium is 0.186

the answer for rubidium is 0.251

the answer is option a.