Which of the following pairs of names and formulas of complexes is not correct?

Potassium hexacyanidoferrate (III) - K₄[Fe(CN)₆]

The correct answer is option 3. Potassium hexacyanidoferrate (III) - K₄[Fe(CN)₆].

To determine which pair of names and formulas of complexes is not correct, we need to carefully analyze the coordination complexes provided:

1. Tetraamminecopper (II) sulphate - \([Cu(NH_3)_4]SO_4\)

Name: Tetraamminecopper(II) sulphate

Formula: \([Cu(NH_3)_4]SO_4\)

Copper(II) ion (\(Cu^{2+}\)) is coordinated by four ammonia \((NH_3)\) ligands, forming the complex ion \([Cu(NH_3)_4]^{2+}\), which pairs with the sulfate ion (\(SO_4^{2-}\)). This is correct.

2. Diamminesilver (I) chloride - \([Ag(NH_3)_2]Cl\)

Name: Diamminesilver(I) chloride

Formula: \([Ag(NH_3)_2]Cl\)

Silver(I) ion (\(Ag^{+}\)) is coordinated by two ammonia \((NH_3)\) ligands, forming the complex ion \([Ag(NH_3)_2]^{+}\), which pairs with a chloride ion \((Cl^-)\). This is correct.

3. Potassium hexacyanidoferrate (III) - \(K_4[Fe(CN)_6]\)

Name: Potassium hexacyanidoferrate(III)

Formula: \(K_4[Fe(CN)_6]\)

The formula \(K_4[Fe(CN)_6]\) corresponds to the anion \([Fe(CN)_6]^{4-}\), which is actually the hexacyanidoferrate(II) complex. The correct name for \(K_4[Fe(CN)_6]\) is potassium hexacyanidoferrate(II). Therefore, this pair is not correct.

4. Potassium amminepentachloridoplatinate (IV) - \(K[Pt(NH_3)Cl_5]\)

Name: Potassium amminepentachloridoplatinate(IV)

Formula: \(K[Pt(NH_3)Cl_5]\)

Platinum(IV) ion (\(Pt^{4+}\)) is coordinated by one ammonia \((NH_3)\) ligand and five chloride \((Cl^-)\) ligands, forming the complex ion \([Pt(NH_3)Cl_5]^{-}\), which pairs with a potassium ion \((K^+)\). This is correct.

Conclusion: The incorrect pair of name and formula is: Potassium hexacyanidoferrate (III) - \(K_[Fe(CN)_6]\).

The correct name for \(K_4[Fe(CN)_6]\) is potassium hexacyanidoferrate(II).