Why are the electron affinities of alkaline earth metals nearly zero?

Why the electron gain enthalpy values of alkaline earth metals are lower or positive?

Why the electron gain enthalpy values of alkaline earth metals are lower (i.e. less negative) or positive?

Why the electron gain enthalpy values of alkaline earth metals are lower (i.e. less negative) or positive?

Why the electron gain enthalpy values of alkaline earth metals are lower (i.e. less negative) or positive?

In a period, from the left to right the electron affinity , increases, but alkaline earth metals have lower electron affinity than alkali metals because

Electronic configuration of alkaline earth metal is

The outer electronic configuration of alkaline earth metals is