If the radius of the hydrogen atom is $53 \, pm$, the radius of the $He^{+}$ ion is closest to $...... \, pm$.

The ionization energy of $He^+$ is $19.6 \times 10^{-18} \ J \ atom^{-1}$. What is the energy of the first stationary state $(n = 1)$ of $Li^{2+}$?

The radius of the $2^{nd}$ orbit of $B^{4+}$ ion is:

For a hydrogen atom,the energy difference between the first and second Bohr orbits is $3B/4$. What is the energy difference between the first and third Bohr orbits?

$A$ $12.75 \ eV$ electron beam is used to bombard gaseous hydrogen at room temperature. The wavelengths emitted belong to which of the following series?

Which of the following transitions has the minimum wavelength?