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

Coordination number of iron in b oth the complexes is sidx and its oxidation state is +3. Electronic configuration of `Fe^(3+)` is :

In the presence of strong `CN^(-)` ligands, 3d electrons pair up leaving on unpared electron. The hybridization due to the presence of one unpaired electron(fig).
In the presence of weak `H_2O` ligand, 3d electrons do not pair up. The hybridizaton is `sp^3d^2` forming an outer -orbital complex containing five unpared electrons (fig). Hence, It is strongly paramagnetic.