Exam-style question
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A hydrogen atom emits an infrared photon when an electron drops from n=7 to n=4. Use the energy-level equation to calculate the photon energy, then link the smaller transition energy to the longer wavelength region.
- A.1.89 eV
- B.2.55 eV
- C.3.40 eV
- D.5.13 eV
Model answer
What a good answer should say
- 2.55 eV
Explanation
Why this works
The transition from n=7 to n=4 has a smaller energy gap than drops to n=1 or n=2. The calculated emitted photon energy is 2.55 eV, so the answer should connect the lower energy change with a longer-wavelength photon rather than only quoting the number.
Common mistake
No common mistake is linked to this question yet.