Question

Three protons coming from excited atomic hydrogen sample are picked up. Their energies are $12.1eV,10.2eV$ and $1.9eV$. These photons must come from

• A. a single atom
• B. two atoms
• C. three atoms
• D. either two atoms or three atoms

Answer 1

The correct option is D either two atoms or three atoms

If the electron jumps from level $n_3$ to $n_1$ then the photon of energy $12.1eV$ is emitted.
If the electron jumps from level $n_3$ to $n_2$ then the photon of energy $1.9eV$ is emitted.
If the electron jumps from level $n_2$ to $n_1$ then the photon of energy $10.2eV$ is emitted.
Clearly these transitions are possible in minimum two atoms or maximum three atoms .