Define ligand. Explain the magnetic properties of `[Ni(CN)_(4)]^(2-)`

Explain important properties of a magnet.

The IUPAC name of [Ni(CN)_(4)]^(2-) is

The EAN of Ni in [Ni(CN)_(4)]^(2-) is

Geometry, hybridisation and magnetic moment of the ions [Ni(CN)_(4)]^(2-),[MnBr_(4)]^(2-) and [FeF_(6)]^(3-) respectively are .