Assertion: [Fe(H2O)6]3+ is strongly paramagnetic whereas [Fe(CN)6]3- is weakly paramagnetic.
Reason: H2O is a strong field ligand and CN- is a weak field ligand.
Answer & explanation
Correct answer: option 3
[Fe(H2O)6]3+ is strongly paramagnetic whereas [Fe(CN)6]3- is weakly paramagnetic.
In case of CN-, 3d electrons pair up leaving one unpaired electron, hybridisation is d2sp3 forming inner orbital complex. In case of H2O (weak ligand), 3d electrons do not pair up, hybridisation is sp3d2 forming an outer orbital complex. As it contains five unpaired electrons so it is strongly paramagnetic.