The ground state energy of a hydrogen atom is $-13.6 \text{ eV}$. When its electron is in the first excited state,its excitation energy is:

Energy of an electron (in $eV$) in the $2^{nd}$ orbit of a $He^{+}$ ion is (in $.6$)?

The ratio of energies of photons produced due to the transition of an electron in a hydrogen atom from its $(i)$ second to first energy level and (ii) highest energy level to second energy level is: (in $3:1$)

When a hydrogen atom is raised from the ground state to the excited state,

In a hydrogen atom,when an electron jumps from the ground state to an excited state,the electron's ...

Due to transitions among its first three energy levels,a hydrogenic atom emits radiation at three discrete wavelengths $\lambda_1, \lambda_2$ and $\lambda_3$ (where $\lambda_1 < \lambda_2 < \lambda_3$). Then,