Assertion : `[Fe(H_(2)O)_(6)]^(3+)` is strongly paramagnetic whereas `[Fe(CN)_(6)]^(3-)` is weakly paramagnetic .
Reason : `H_(2)O` is a weak ligand and `CN^(-)` is a strong field ligand .

Explanation

`H_(2)O` is a weak ligand, so it does not cause pairing of electrons hence paramagnetic behaviour of `[Fe(H_(2)O)_(6)]^(3+)`
`CN^(-)` is a strong ligand, so it causes the pairing of electrons, hence diamagnetic behaviour of `[Fe(CN)_(6)]^(3-)`