Which of the transitions in the hydrogen atom energy-level diagram shown here is not possible?
A)a
B)b
C)c

Question

Which of the transitions in the hydrogen atom energy-level diagram shown here is not possible? 
A)a 
B)b 
C)c

Quizplus · Accepted Answer

Transition d is not possible because it violates the energy conservation principle. The energy difference between levels n=2 and n=1 is 10.2 eV, and the energy difference between levels n=1 and n=3 is 12.1 eV. Therefore, to move from level n=2 to level n=3, the atom would need to absorb a photon with exactly 1.9 eV of energy, which is not possible since no such photon exists in the electromagnetic spectrum.

Which of the Transitions in the Hydrogen Atom Energy-Level Diagram