Out of Fe²⁺, Co²⁺, Cr³⁺, Ni²⁺, the one which shows the lowest magnetic moment is:
[Atomic number: Fe = 26, Co = 27, Ni = 28, Cr = 24]
Magnetic moment ∠unpaired electrons.
Fe²⁺
Co²⁺
Cr³⁺
Ni²⁺
With a 3d⁸ configuration, Ni²⁺ exhibits 2 unpaired electrons, resulting in a lower magnetic moment than other species.
The IUPAC name for the complex \( [\text{Co}(\text{ONO})(\text{NH}_3)_5]\text{Cl}_2 \) is