What is the smallest possible value of the principal quantum number n for an electron in an atom?

• A. -1
• B. 1
• C. 0
• D. 2

Answer: (B)

Verified step by step guidance

1. Understand that the principal quantum number, denoted as \(n\), describes the main energy level or shell of an electron in an atom.
2. Recall that \(n\) can only take positive integer values: \(n = 1, 2, 3, \ldots\); it cannot be zero or negative.
3. Recognize that the smallest possible value of \(n\) corresponds to the lowest energy level, which is the first shell closest to the nucleus.
4. Therefore, the smallest possible value of the principal quantum number \(n\) is 1.
5. Values like 0 or negative numbers are not allowed for \(n\) because they do not correspond to any physical electron energy level in quantum mechanics.