The light of wavelength $242 \, nm$ is required to remove an electron from a $Na$ atom. What is the ionization energy of the sodium atom in $kJ \, mol^{-1}$?

The energy of the second Bohr orbit of the hydrogen atom is $-3.4 \ eV$. The energy of the fourth Bohr orbit of the $He^{+}$ ion will be: (in $eV$)

What is the ratio of the radii of the second orbit for $H$,$He^{+}$,and $Li^{2+}$?

Which orbit of $Be^{+3}$ has the same orbit radius as that of the ground state of hydrogen atom?

When electronic transition occurs from a higher energy state to a lower energy state with an energy difference equal to $\Delta E$ electron volts,the wavelength of the emitted line is approximately equal to

Select the incorrect graph for the velocity of an electron $(e^-)$ in an orbit vs. $Z$,$\frac{1}{n}$,and $n$.