Answer:
Nitrogen
It has the least number of protons in the group hence making it smaller
Explanation:
According to periodic table, electronegativity increases across the period and decreases down the group.
Electronegativity is the tendency of an element to accept electrons towards itself.
In this group of elements, nitrogen has the highest electronegativity because it has the least number of protons in the group. Increase in the number of protons decreases an elements electro negative value.
The least electronegative element in that group is Antimony (Sb).
Electronegativity increases across the period and decreases down the group while electropositivity decreases across the period and increases down the group.
