6.941u? Sorry if I get it wrong
4d¹⁰ 5s² 5p⁶ is the electron configuration
The answer is (1) natural transmutation. When Co-60 undergoes beta decay (be it beta positive or beta negative), the product is another element (Fe or Ni). Transmutation is when an element turns into another element via a nuclear process. Since this occurs without the aid of another agent that causes the nuclear change (e.g. a neutron source), it is natural transmutation.
The concept of resonance is required for certain molecules because the localized electron model assumes electrons are located between a given pair of atoms in a molecule.