Question

Sodium has lower affinity than chlorine atom

Answer 1

Electron Affinity depends on Atomic size of an atom. If the atomic size is smaller then the electron affinity is greater and vice versa. Since atomic decrease from left to right in a periodic

Answer 2

Electron Affinity depends on Atomic size of an atom. If the atomic size is smaller then the electron affinity is greater and vice versa.
Since atomic decrease from left to right in a periodic table. And Na occurs before Cl in the same period.
Therefore, sodium have low electron affinity than chlorine atom.