Question

An electron is at ground state of the $H$ atom. Minimum energy required to excite the $H$ atom into second excited state is

• A. $10.2eV$
• B. $3.4eV$
• C. $13.6eV$
• D. $12.1eV$

Answer 1

Answer: (D)

$12.1eV$

Answer 2

According to question, For an electron jump from first excited state to second
Energy required, $\Delta E=E_{3}-E_{1}$
$=\frac{-13.6}{(3)^{2}}-(-13.6)$
$\left[\because\right.$ Energy of excited 2 nd excited state, $\left. E_{3}= \frac{-13.6}{9}\right]$
$\Rightarrow \Delta E=-1.5+13.6=12.1\, eV$