With the help of crystal field theory, predict the number of unpaired electrons in `[Fe(CN)_6]^(4-)` and `[Fe(H_2O)_6]^(2+)`.

Explanation

In both complex, Fe is present as Fe (II). It has `d^6` configuration i.e. four unpaired electrons. Now `CN^(-)` is a strong ligand. So these electrons will pair up i.e No. ofunpaired electrons= 0. But on the other hand `H_2O` is a weak ligand, electrons will not pair up i.e. no. of unpaired electrons =4.