Statement(I) : Nitrogen is inertStatement(I) : Nitrogen has the highest IP1 among 15th group elements

It is the atoms which participate in chemical reactions but not molecules.so to convert N2 molecule to Nitrogen atoms very large energy (945KJ/mole) is required.Chemical inertness of N2 is due to large bond dissociation enthalpy.Down the group , IP1 decreases.IP1 of N > P > As > Sb > Bi.