The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is x × 10^-8 m. The value of x is \ \ \…

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