The radius (in $\mathring{A}$) of the $3^{rd}$ Bohr orbit in $Li^{2+}$ ion is closest to $......$ [Given: Atomic number of $Li = 3$]

The ratio of the area covered by the second orbital to the first orbital is

The binding energy of an $e^-$ in the ground state of a hydrogen atom is $13.6 \ eV$. The energy required to remove an electron from the ground state of a $He^+$ ion is:

The first use of quantum theory to explain the structure of the atom was made by

The angular momentum of an electron in the $7^{th}$ Bohr orbit of a hydrogen atom is given by:

Find out the distance between the $2^{nd}$ and $3^{rd}$ orbit of the $H^{-}$ ion.