Answer
See the explanation
Work Step by Step
The three elements are:
a. The ground-state electron configuration is \([\mathrm{Kr}] 5 s^{2} 4 d^{10} 5 p^{4}\) corresponds to the element Tellurium (Te), atimic number $52$.
b. The ground-state electron configuration is \([\mathrm{Ar}] 4 s^{2} 3 d^{10} 4 p^{2}\) corresponds to the element Germanium (Ge), atomic number $32$.
c. An excited state of this element has the electron configuration \(1 s^{2} 2 s^{2} 2 p^{4} 3 s^{1}\). Ground state of this configuration would be \(1 s^{2} 2 s^{2} 2 p^{5} \), therefore a total of 9 electrons.
This corresponds to the element Fluorine (F), atomic number $9$..
