Answer
See the detailed answer below.
Work Step by Step
Since lithium has an atomic number of 3, so $Z=3$.
Thus,
$$E_n=-\dfrac{13.6 Z^2}{n^2}$$
$$E_n=\dfrac{-122.4}{n^2}$$
Therefore, the levels of energy from the lowest to the highest are:
$$E_1=\dfrac{-122.4}{1^2}=\color{red}{\bf -122.4}\;\rm eV$$
$$E_2=\dfrac{-122.4}{2^2}=\color{red}{\bf -30.6}\;\rm eV$$
$$E_3=\dfrac{-122.4}{3^2}=\color{red}{\bf -13.6}\;\rm eV$$
$$E_4=\dfrac{-122.4}{4^2}=\color{red}{\bf -7.65}\;\rm eV$$
$$E_5=\dfrac{-122.4}{5^2}=\color{red}{\bf -4.896}\;\rm eV$$
$$E_6=\dfrac{-122.4}{6^2}=\color{red}{\bf -3.4}\;\rm eV$$
$$E_\infty=\dfrac{-122.4}{\infty^2}=\color{red}{\bf 0}\;\rm eV$$
See the figure below.
