Which level of the single ionized carbon has

(2)

Energy of $\mathrm{H}$-atom is $\mathrm{E}=-13.6 \mathrm{Z}^{2} / \mathrm{n}^{2}$

for $\mathrm{H}$-atom $\mathrm{Z}=1 \&$ for ground state, $\mathrm{n}=1$

$\Rightarrow \mathrm{E}=-13.6 \times \frac{1^{2}}{1^{2}}=-13.6 \mathrm{eV}$

Now for carbon atom (single ionised), $Z=6$

$\mathrm{E}=-13.6 \frac{\mathrm{Z}^{2}}{\mathrm{n}^{2}}=-13.6 \quad$ (given)

$\Rightarrow n^{2}=6^{2} \Rightarrow n=6$