From the information below, identify element $\mathrm{X}$.
a. The wavelength of the radio waves sent by an FM station broadcasting at $97.1 \mathrm{MHz}$ is $30.0$ million $\left(3.00 \times 10^{7}\right)$ times greater than the wavelength corresponding to the energy difference between a particular excited state of the hydrogen atom and the ground state.
b. Let $V$ represent the principal quantum number for the valence shell of element $X$. If an electron in the hydrogen atom falls from shell $V$ to the inner shell corresponding to the excited state mentioned above in part a, the wavelength of light emitted is the same as the wavelength of an electron moving at a speed of $570 . \mathrm{m} / \mathrm{s}$
c. The number of unpaired electrons for element $\mathrm{X}$ in the ground state is the same as the maximum number of electrons in an atom that can have the quantum number designations $n=2$, $m_{\ell}=-1$, and $m_{s}=-\frac{1}{2}$
d. Let $A$ equal the charge of the stable ion that would form when the undiscovered element 120 forms ionic compounds. This value of $A$ also represents the angular momentum quantum number for the subshell containing the unpaired electron(s) for element $\mathrm{X}$.