Final answer:
Upon calculating the effective atomic number for each given complex ion using the atomic numbers of Zn, Fe, and Co and the electron donations from their respective ligands, it was found that none of the options has an EAN of 35. Therefore, there seems to be an error in the question or provided options.
Step-by-step explanation:
The student is asking to identify a complex ion in which the effective atomic number (EAN) of the central metal ion is 35. The effective atomic number is the sum of the atomic number of the metal plus the number of electrons it gains from its ligands (assuming each ligand donates two electrons). By individually calculating the effective atomic number for each of the given complexes, we can determine the complex ion with an EAN of 35.
Complex a: [Zn(NH₃)₄]²+
Zn has an atomic number of 30. In this complex, Zn is in a +2 oxidation state, and with four NH₃ ligands, each donating a pair of electrons, the EAN is 30 (atomic number) + 4*2 (8 from ligands) = 38.
Complex b: [Fe(CN)₆]⁴-
Fe has an atomic number of 26. In this complex, Fe is in a +2 oxidation state, and with six CN ligands, each donating a pair of electrons, the EAN is 26 (atomic number) + 6*2 (12 from ligands) = 38.
Complex c: [Fe(CN)₆]³-
Fe has an atomic number of 26. In this complex, Fe is in a +3 oxidation state, and with six CN ligands, the EAN is 26 (atomic number) + 6*2 (12 from ligands) = 38.
Complex d: [Co(NH₃)₆]³+
Co has an atomic number of 27. In this complex, Co is in a +3 oxidation state, and with six NH₃ ligands, each donating a pair of electrons, the EAN is 27 (atomic number) + 6*2 (12 from ligands) = 39.
Unfortunately, none of the given complexes have an EAN of 35. Therefore, there must be an error in the question or the given options since none of them match the required EAN of 35.