Question

Let the potential energy of a hydrogen atom in the ground state be zero. Then its energy in the first excited state will be

• A. $10.2eV$
• B. $13.6eV$
• C. $23.8eV$
• D. $27.2eV$

Answer 1

Answer: (C)

$23.8eV$

The total energy of hydrogen atom in ground state is $-13.6eV$.

In first excited state total energy is $-3.4eV$.

Now if potential energy in ground state($-27.2$) is taken as zero then the whole energy spectrum will be shifted by $27.2eV.$
So, energy in first excited state will be:
$-3.4+27.2=23.8eV$