for \(H\) -atom \(Z =1 \&\) for ground state, \(n =1\)
\(\Rightarrow E =-13.6 \times \frac{1^{2}}{1^{2}}=-13.6 eV\)
Now for carbon atom (single ionised), \(Z=6\)
\(E=-13.6 \frac{ Z ^{2}}{ n ^{2}}=-13.6 \quad\) (given)
\(\Rightarrow n ^{2}=6^{2} \Rightarrow n =6\)
[Rhc=13.6 eV, $\mathrm{hc}=1242 \mathrm{eV} \mathrm{nm}, \mathrm{h}=6.6 \times 10^{-34} \mathrm{J-s}$ અને હાઈડ્રોજન પરમાણુનું દળ $\sim 1.6 \times 10^{-27} \mathrm{~kg}$ લો.]