In a group, electronegativity decreases from top to bottom due to the increase in the atomic size. In a period, electronegativity increases from left to right due to decrease in size and increase in nuclear charge. So, halogens are more electronegative than other groups, therefore, increasing order of electronegativity is as follows B<C<S<Cl Boron (B) (belongs to 13 group) Carbon (C) (belongs to 14 group) Sulphur ( S) (belongs to 16 group) Chlorine (Cl) (belongs to 17 group)