Which of the alkaline earth metals has the smallest electronegativity

-Barium(Ba)

Explanation:-

Electro negativity means the ability to attract ans take electron.(Highest in Fluorine)

The halogens has highest EN than other families as they need only 1 electron to complete octet.Alkaline earth metals such as Be,Mg,Ca,Sc,Ba,Ra. They have 2 electrons in their valence shell but .

If we see their Electronic Configuration

And so on

The s subshell is completely filled (Duplet)So they are more stable .So they less attract electron as they has less EN