Answer the following questions: In an atom X, electrons absorb the energy from an external source…

In an atom X, electrons absorb the energy from an external source. This energy “excites” the electrons from a lower-energy level to a higher-energy level around the nucleus of the atom. When electrons return to the ground state, they emit photons. Figure 15 below is the energy level diagram of atom X with three energy levels, $E_1 = 0\cdot00\text{ eV}$, $E_2 = 1\cdot78\text{ eV}$ and $E_3 = 2\cdot95\text{ eV}$. The ground state is considered 0 eV for reference. What wavelength of radiation is needed to excite the atom to energy level $E_2$ from $E_1$? (Application)

According to Bohr’s theory of hydrogen atom, calculate (Application) (1) angular momentum of the electron in second Bohr orbit. (2) radius of the third Bohr orbit.