In S_N2 reactions, the correct order of reactivity for the following compounds:
CH₃Cl, CH₃CH ₂Cl, (CH₃)₂CHCl and (CH₃)₃CCl is:

The equation which is balanced and represents the correct product(s) is :

The octahedral complex of a metal ion M³⁺ with four monodentate ligands L₁, L₂, L₃ and L₄ absorb wavelengths in the region of red, green, yellow and blue, respectively. The increasing order of ligand strength of the four ligands is :

Which series of reactions correctly represents chemical relations related to iron and its compound?