Which principal quantum number (n) corresponds to the energy level closest to the nucleus?

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

Answer: (A)

Verified step by step guidance

1. Understand that the principal quantum number \(n\) indicates the main energy level or shell of an electron in an atom.
2. Recall that the energy levels are quantized and increase in energy as \(n\) increases, meaning electrons with higher \(n\) values are farther from the nucleus.
3. Recognize that the energy level closest to the nucleus corresponds to the lowest principal quantum number, which is \(n = 1\).
4. Note that \(n = 1\) is called the first energy level or K-shell, and it has the lowest energy and smallest radius around the nucleus.
5. Therefore, among the given options, the energy level closest to the nucleus is the one with \(n = 1\).