An electron-dot diagram is a graphical representation of the valence electrons of a certain element. The chemical symbol of an element placed in the middle and the valence electrons are represented by dots. The number of dots is equal to the number of valence electrons. So in your illustration, you can see that there are 5 dots all in all. This indicates that this mystery element has 5 valence electrons. Elements in Group 5A or the Nitrogen Group.
Among the choices, only Arsenic is under Group 5A.
