The mass number represents the summation of the number of protons and the number of neutrons in the nucleus of an atom.
We are given that the mass number is 64 and that the number of neutrons is 35. Therefore:
number of protons = 64 - 35 = 29 protons
In ground state, number of protons in an atom is equal to the number of electrons. Therefore,
number of electrons = 29 electron
Using the periodic table, we will find that the element that has 29 electrons in ground state is copper.
The nuclide symbol of copper is shown in the attached image.
For [Ni(en)³]²⁺ which is purple, the crystal field splitting energy is greater than the complex ion, [Ni(H₂O)₆]²⁺ which is green in color.
When a Lewis base id attached to the metal ion by covalent bond, then the complex ion is formed and when these complex ions are present with other ions of opposite charge or neutral charge, they will make complex compounds.
Answer is Ti
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