Question

An electron in a hydrogen atom in its ground state absorbs energy equal to the ionisation energy of $L{i}^{\text{+ 2}}$.
The wavelength of the emitted electron is:

• A. $114.2\times {10}^{-10}$
  
• B. $1.17\stackrel{\text{o}}{\text{A}}$
• C. $2.32\times {10}^{-9}\text{nm}$
• D. $3.33\text{pm}$

Answer 1

The correct option is B $1.17\stackrel{\text{o}}{\text{A}}$

Energy of emitted electron $=E_{L{i}^{2+}}-E_H=13.6\left(3^2\right)-13.6=13.6\times 8$

$\lambda =\frac{hC}{E}=\frac{6.63\times {10}^{-34}\times 3\times {10}^8\times 1.6\times {10}^{-19}}{13.6\times 8}=1.17\mathring{A}$
Option B is correct.