Question

The energy to knock out the electron in the third orbit of a hydrogen atom is equal to

• A. $13.6eV$
• B. $+\frac{13.6}{9}eV$
• C. $-\frac{13.9}{3}eV$
• D. $-\frac{3}{13.6}eV$

Answer 1

Answer: (B)

$+\frac{13.6}{9}eV$

Energy required to knock out the electron in the $n^{th}$ orbit $=+\frac{13.6}{n^2}eV$

$E_3=+\frac{13.6}{3^2}eV$

$\Rightarrow E_3=+\frac{13.6}{9}eV$.