Question

If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of $L{i}^{++}$ is

• A. 122.4 eV
• B. 30.6 eV
• C. 13.6 eV
• D. 3.4 eV

Answer 1

The correct option is B 30.6 eV

Using $E_n=-\frac{13.6\times Z^2}{n^2}eV$
For first excited state n = 2 and for $L{i}^{++}$, Z = 3
$\therefore E=-\frac{13.6}{2^2}\times 3^2=-\frac{13.6\times 9}{4}=-30.6eV$.