In the hydrogen atom, the principal quantum number n specifies the energy level of an electron. If an electron originated from the third energy level before making a transition, what is the value of n for its initial state?

• A. n = 2
• B. n = 3
• C. n = 1
• D. n = 4

Answer: (B)

Verified step by step guidance

1. Understand that the principal quantum number \(n\) represents the energy level or shell of an electron in a hydrogen atom.
2. Identify that the problem states the electron originated from the third energy level, which means the initial value of \(n\) corresponds to that energy level.
3. Recall that the principal quantum number \(n\) is an integer starting from 1 (ground state), so the first energy level is \(n=1\), the second is \(n=2\), and the third is \(n=3\).
4. Therefore, if the electron started in the third energy level, its initial principal quantum number \(n\) must be 3.
5. This means the correct value of \(n\) for the initial state of the electron is \(n=3\).