The ratio of ground state energy of $Li^{2+}$,$He^{+}$,and $H$ is:

The number of absorption lines in the given figure will be .......

If '$X$' is the ionization energy of hydrogen,then the energy required for the excitation of a $Li^{2+}$ electron from the $2^{nd}$ excited state to the $5^{th}$ excited state is:

The work function of sodium metal is $4.41 \times 10^{-19} \ J$. If photons of wavelength $300 \ nm$ are incident on the metal,the kinetic energy of the ejected electrons will be $\left( \dots \right) \times 10^{-21} \ J$. (Given: $h = 6.63 \times 10^{-34} \ J \cdot s; c = 3 \times 10^{8} \ m/s$)

In which orbit of the Bohr model of the hydrogen atom is the speed of the electron maximum?

Which of the following species has the same radius as that of the hydrogen atom in the $n = 1$ state?