`[Ni(CO)_4]` is tetrahedral but diamgagnetic why?

Which one is tetrahedral:

[Cr(NH_(3))_(6)]^(3+) is paramagnetic while [Ni(CN)_(4)]^(2-) is diamagnetic. Explain why?

Explain on the basis of valence bond theory that [Ni(CN)_(4)]^(2-) ion with square planar structure is diamagnetic and the [NiCl_(4)]^(2-) ion with tetrahedral geometry is paramagnetic.

[NiCl_(4)]^(2-) is paramagnetic while [Ni(CO)_(4)] is diamagnetic though both are tetrahedral. Why?

Write IUPAC name of the complex [Cr(NH_(3))_(4)Cl_(2)]Cl. What type of isomerism is exhibited by the complex [Co(en)_(3)]^(3+) (en = ethane - 1, 2 - diamine) ? Why is [NiCl_(4)]^(2-) paramagnetic but [Ni(CO)_(4)] is diamagnetic ? (Atomic no : Cr = 24, Co = 27, Ni = 28)

Explain why [Ni(CN)_4]^(2-) and [Ni(CO)_4] having same magnetic property through they differ in geometry?

Why is [NiCl_(4)]^(2-) paramagnetic while [Ni(CN_(4))]^(2-) is diamagnetic ? (At. No. of Ni = 28)

Amongst [NiCl_(4)]^(2-),[Ni(H_(2)O)_(6)]^(2+),[Ni(PPh_(3))_(2)Cl_(2)],[Ni(CO)_(4)]and[Ni(CN)_(4)]^(2-) , the paramagnetic species are

[Ni(NH)_(4)]^(2-) is diamagnetic but [NiCl_(4)]^(2-) is paramagnetic. Give the hybridisation of Ni^(2+) in the given complex ions.

Which one of CHCl_(3) and C Cl_(4) is regular tetrahedral in shape?