Question

What is the binding energy of an electron in the first orbit of ${Li}^{2+}$ is

• A. $13.6eV$
• B. $122.4eV$
• C. $-13.6eV$
• D. $-122.4ev$

Answer 1

The correct option is D $-122.4ev$

$\begin{array}{c}\text{We know,}\\ \text{Energy of electron in Bohr's theory is}\end{array}$

$E=\left(\frac{-13\cdot 6z^2}{n^2}\right)ev$

$\begin{array}{cc}\text{for}& L{i}^{2+}\\ & z=3\\ & n=1\end{array}$

$\begin{array}{c}E=\frac{-13.6\times 9}{1}ev\\ E=-122.4ev\end{array}$