Scale to be considered for comparing electronegativities of nitrogen and chlorine
Please take into account that there are a lot of different ways for calculating electronegativity.

1) Pauling obtains it by comparing the energies of dissociation of the three diatomic molecules AA, BB, and AB, stating that H electronegativity  is 2.1 !  Unit : √energy

2) For Mulliken, it is the average value between the electronic affinity and the first ionization energy of the atom. Unit : energy

3) For Allred - Rochow, it is the force acting between a valence electron and the charge of the atom when the other valence electrons are removed. Unit : force

4) For Sanderson, it is the average electronic density of an atom divided by the average electronic density of the corresponding atom of inert gas.No unit.