Question

n	Energy above ground state
3	7 eV
2	3 eV
1	0 eV

There are three lowest energy levels of an atom, if atom is in $n=3$ energy level. What is the possible energy of photon emitted in single transition ?

• A. 3e V only
• B. 4e V only
• C. 7e V only
• D. 4e V or 7e V only
• E. 3e V or 4e V only

Answer 1

The correct option is D 4e V or 7e V only

The possible single transitions that can occur are $n_3\to n_2$ and $n_3\to n_1$.

Thus the possible energies of photons are $7eV-3eV=4eV$

and $7eV-0eV=7eV$