The radius of the fourth orbit in $He^{+}$ ion is '$R_1$' $pm$ and the radius of the third orbit in $Li^{2+}$ ion is '$R_2$' $pm$. The value of $(R_1 - R_2)$ in $pm$ is:

The wave number of the spectral line in the emission spectrum of hydrogen will be equal to $\frac{8}{9}$ times the Rydberg's constant if the electron jumps from

How many spectral lines are obtained when an electron transitions from the $8^{th}$ orbit to the $1^{st}$ orbit in a hydrogen atom?

The wavenumber associated with the maximum energy in the Balmer series will be......

Calculate the wavelength of the emitted radiation when an electron transitions from $n = 3$ to $n = 2$ in a hydrogen atom. To which region does this radiation belong?

The energy of an electron in the first Bohr orbit of the $H$ atom is $-13.6 \ eV$. The magnitude of the energy value of an electron in the first excited state of $Be^{3+}$ is $.......... \ eV$ $(nearest \ integer \ value)$.