From the statements below, identify which one(s) is/are incorrect:

(i) Electronegativity is measured in kJ/mol units.

(ii) Electron affinity is different from electronegativity.

(iii) Electronegativity is the tendency to attract shared electrons when forming a chemical bond.

(iv) The most electronegative element in the periodic table is helium.

(v) The least electronegative element in the periodic table is radon.