According to Bohr's theory,the angular momentum of an electron in the $5^{th}$ orbit is ....... (in $h/\pi$)

The wavelength of the first line of the Lyman series for hydrogen is $1216 \ \mathring{A}$. The wavelength of the first line of the same series for a $10$ times ionized sodium atom $(Z = 11)$ will be ......... $\mathring{A}$.

When an electron jumps from $L$ to $K$ shell,what happens to the energy?

Wave number of a spectral line for a given transition is $y \ cm^{-1}$ for $He^{+}$,then its value for $Li^{2+}$ for the same transition is

When an electron drops from a higher energy level to a lower energy level,then

If the first emission in the Lyman series of a hydrogen atom occurs at $121.5 \ nm$,what will be the energy difference between the first and second orbits in $kJ/mol$?