Periodic Table And Periodicity

First and second ionization enthalpies of lithium are $520 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $7297 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. Energy required to convert 3.5 mg lithium (g) into $\mathrm{Li}^{2+}(\mathrm{g})\left[\mathrm{Li}(\mathrm{g}) \rightarrow \mathrm{Li}^{2+}(\mathrm{g})\right]$ is $\_\_\_\_$ $\mathrm{kJ} \mathrm{mol}^{-1}$. (nearest integer)

[Molar mass of $\mathrm{Li}=7 \mathrm{~g} \mathrm{~mol}^{-1}$ ]