Calculate the energy associated with the third orbit of $He^{+}$.

Going from $K$-shell to $N$-shell in case of $H$-atom :

The longest wavelength of light that can be used for the ionisation of lithium atom $(Li)$ in its ground state is $x \times 10^{-8} \, m$. The value of $x$ is $.....$ (Nearest Integer)
(Given : Energy of the electron in the first shell of the hydrogen atom is $-2.2 \times 10^{-18} \, J$; $h = 6.63 \times 10^{-34} \, Js$ and $c = 3 \times 10^{8} \, ms^{-1}$ )

The energy of an $H$ atom in the $n^{th}$ orbit is $E_n$. What will be the energy of the $n^{th}$ orbit of a singly ionized helium atom $(He^+)$?

The ratio of the velocity of an electron in the second orbit of $He^{+}$ to the third orbit of $B^{4+}$ is:

If the wavelength of the first line in the Balmer series is $656 \ nm$,then the wavelength of its second line and limiting line respectively are