Question

The ground state energy of hydrogen atom is $-13.6\text{eV}$. When its electron is in the first excited state, its excitation energy is

• A. $0$
• B. $6.8\text{eV}$
• C. $3.4\text{eV}$
• D. $10.2\text{eV}$

Answer 1

The correct option is D $10.2\text{eV}$

Ground state energy of hydrogen $E_0=-13.6$eV

Energy in first excited state
$E_n=\frac{-13.6}{n^2}\text{eV}$
or, $E_2=-3.4\text{eV}$

$\therefore$ Required energy to excite electron in first excited state
$E=E_2-E_0=10.2\text{eV}$

Hence , option $\left(A\right)$ is correct.