Calculate the radius of the first orbit of $Li^{2+}$. (in $pm$)

The ground and first excited state energies are $E_1$ and $E_2$ respectively. Which pair of species has the same energy? [Note that energy is indicated in the bracket].

Find the frequency of light that corresponds to photons of energy $5.0 \times 10^{-5} \ erg$.

For the Paschen series, the values of $n_1$ and $n_2$ in the expression $\Delta E = R h c \left( \frac{1}{n_1^2} - \frac{1}{n_2^2} \right)$ are:

What is the ratio of the radii of the second orbit for $H$,$He^{+}$,and $Li^{2+}$?

Given the energy equation $E_n = -313.6/n^2$,if $E_n = -34.84$,which of the following could be the value of $n$?