Define ferromagnetism, paramagnetism and diamagnetism, and determine whether the following complexes a) AgCl b) [Fe(CN)6]4- c) [Mn(CN)6]4- d) Co(H2O)6Cl2 are ferromagnetic, diamagnetic or paramagnetic giving a full justification for your reasoning.

Ferromagnetism is the type of magnetism in which the magnetic moments of certain atoms align with the external magnetic field. The examples of ferromagnetic metal are iron, nickel and cobalt.Paramagnetism is a form of a weak magnetism, where the metal ions are weakly attracted to external magnetic field. Paramagnetic metal ions have unpaired electrons on their d orbitals and the strength of that magnetism depends on the strength of the ligand, which influences whether the energy splitting of the d orbitals is low or high spin.Diamagnetism is a property of the transition metal complexes that are not attracted to the external magnetic field, due to the fact that there is no unpaired electrons in the d orbitals of the metal ion.
a) AgCl -> Ag+Cl- , hence Ag(I), configuration : 4d10, therefore no unpaired electrons, and the complex is diamagneticb) [Fe(CN)6]4- : Fe (II), configuration 3d6. CN- is a strong field ligand causing large energy splitting, hence the complex is low spin, there is 3 pairs of electrons in the t2g orbitals (lower in energy), hence again no unpaired electrons which means the complex is diamagneticc) [Mn(CN)6]4- : Mn(II), configuration 3d5. The complex is low spin, but there is one unpaired electron, hence the complex is paramagneticd) Co(H2O)6Cl2 : Co(II), configuration 3d7, high spin, hence paramagnetic, because 3 unpaired electrons present in the d orbitals.