The chemical elements are arranged in the order of increasing electronegativities in the sequence

Electronegativity increases as we move from left to right in a period so phosphorus is more electronegative than silicon and bromine is more electronegative than selenium and electronegetivity decreases ss we descend the group. ∴ Nitrogen is the most electronegative element of the given elements. ∴ The observed order is  Si, P,Se,Br,N