Question

A photon of energy 12.75 ev is completely absorbed by a hydrogen atom initially In ground state. The principle quantum number of the excited state is

• A. 1
• B. 3
• C. 4
• D. $\infty$

Answer 1

Answer: (C)

4

Transition energy for Hydrogen atom is given by:

$\Delta E=-R(1/n_2^2-1/n_1^2)$

where $R=13.6ev,n_1=1,n_2=n$

$12.75=-13.6(1/n^2-1)$

$-0.9375+1=1/n^2$

$n^2=16$

$n=4$

So, the corret option is $C$.