The correct order of the spin-only magnetic moment of metal ions in the following low-spin complexes, [V(CN)₆]^4–,[Fe(CN)₆]^4–, [Ru(NH₃)₆]³⁺, and [Cr(NH₃)₆]²⁺ , is :

The lathanide ion that would show colour is :

The size of the iso-electronic species Cl^–,  Ar and Ca²⁺ is affected by :

In order to oxidise a mixture of one mole of each of FeC₂O₄, Fe₂(C₂O₄)₃, FeSO₄ and Fe₂(SO₄)₃ in acidic medium, the number of moles of KMnO₄ required is :