Question

Which one Fe2+, Fe3+ is more paramagnetic and why?

Answer 1

Fe³⁺ will be more paramagnetic.   Paramagnetism is shown when a charged particle moves in a magnetic field in presence of an external magnet.  That force is given by F = q v B (v = velocity, B = magnetic field, q = electron charge). 

Fe element without any positive charge on it and  in its natural state has two unpaired electrons in its orbital configuration [Argon] 3d⁶ 4s².   The electrons are attracted towards the magnets. Hence it is paramagnetic.

Fe²⁺ has no free electrons.  Hence it is diamagnetic in general.  In certain chemical compounds with  Iron (II), some changes may occur in the orbit of electrons in the 3d shell and those compounds may become faintly paramagnetic.

Fe³⁺ has one electron unpaired.  Hence  it is paramagnetic.