Given : Hydrogen like species, $\mathrm{Li}^{2+}$
Spherically symmetric state, $S_1 \Rightarrow s$-orbital
$S_1$ has radial node $1 \Rightarrow 2 s \quad$ (No. of radial node $=1=n-l-1$, so $n=2$ ) Species undergoes state $S_2$
$S_2$ has energy equal to the ground state energy of $\mathrm{H}$-atom $=-13.6 \mathrm{eV}$
So, $\quad-13.6=-13.6\left(\frac{3^2}{n^2}\right)$
$n=3$
Again radial node $=1=n-1-1$
or $1=3-l-1 \quad$ so $\quad l=1$
It suggests $S_2$ is $3 p$