Final answer:
The energy difference between two electrons both in the n=3 state of molecules with different bond lengths is 0 eV, as energy levels are determined by the quantum number and not bond length in this context.
Step-by-step explanation:
To calculate the energy difference between two electron states in different molecules, we apply the formula En = (-13.6 eV/n²) for the energy levels of an electron in a hydrogen-like atom, where n is the principal quantum number.
For both electrons in the n=3 state, the energy is calculated as:
E = -13.6 eV / 3² = -13.6 eV / 9
E = -1.5111... eV
This energy value is constant for a given n and does not depend on the bond length. Because both electrons are in the same quantum state, n=3, and the question asks us to ignore bond angles and only consider the energy levels, the energy difference between the two states is 0 eV. The bond length does not affect the energy of a specific quantum state in this scenario.