Low oxidation state of metals in their complexes are common when ligands :

$$\mathrm{Fe}^{3+}$$ cation gives a prussian blue precipitate on addition of potassium ferrocyanide solution due to the formation of :

The metal complex that is diamagnetic is (Atomic number: $$\mathrm{Fe}, 26 ; \mathrm{Cu}, 29)$$

The correct order of energy of absorption for the following metal complexes is :

A : [Ni(en)₃]²⁺ , B : [Ni(NH₃)₆]²⁺ , C : [Ni(H₂O)₆]²⁺