Which of the following name is correct?

The correct name among the given options is: (3) Na2[Ni(EDTA)]; Sodium ethylenediaminetetraacetato nickelate (II)
Let's verify the names of each option:

(a) [Cu(H₂O)(NH₃)]Br₂; Amminoaquodibromocopper (I) - This name is incorrect because it doesn't follow the proper naming conventions for coordination complexes. The correct name should be "Aquaamminebromocopper (I).

(b) Na₃[Al(C₂O₄)₃]; Trisodium trioxalatoaluminate (III) - This name is incorrect. The correct name is: Na₃[Al(C₂O₄)₃]; Sodium trisoxalatoaluminate(III). The ligand in this complex is oxalate \(C2O4^{2-}\), and there are three oxalate ligands coordinated to the aluminum \(Al^3+\) ion. The oxidation state of aluminum is III. The prefix "tris" indicates three oxalate ligands, and "sodium" denotes that the complex has three sodium (Na⁺) ions as counterions.

(c) Na₂[Ni(EDTA)]; Sodium ethylenediaminetetraacetato nickelate (II) - This name is correct. It properly describes the complex with its ligands (EDTA), the metal (nickelate), and its oxidation state (II).

(d) [Co(NH₃)₅ONO]SO₄; Pentaamminenitrocobalt (III) sulphate - This name is incorrect because it misses the proper prefix for the nitrite ligand. The correct name should be "Pentaamminenitrocobalt (III) sulphate."