Ni^2+ is a d8 ion. It could exist in either a square planar or a tetrahedral geometry depending on the identity of the ligand. However, strong field ligands often lead to a square planar geometry owing to a greater crystal field splitting.
From the splitting diagrams of nickel II ion in tetrahedral and square planar geometries, it can easily be seen that a diamagnetic complex only arises from the square planar geometry.
Note that both tetrahedral and square planar geometries involve a coordination number of four.
1) Calculate the molar weight. 12.000 + 4*(35.45) 2) Divide 15.0 by the molar weight to get moles 3) Multiply by Avogado's number of get the number of molecules.
Be careful on this one! Mass is always conserved, based on the law of conservation of mass. Since their was a change in state, we went from a solid to a gas, so, the weight would be lighter, not the mass.