How many possible values of the magnetic quantum number, m_l, are allowed for an electron in a 2s subshell?

• A. 2
• B. 3
• C. 0
• D. 1

Answer: (D)

Verified step by step guidance

1. Recall that the magnetic quantum number \(m_l\) depends on the azimuthal quantum number \(l\), which defines the subshell type (s, p, d, f, etc.).
2. Identify the value of \(l\) for the 2s subshell. Since it is an s subshell, \(l = 0\).
3. Use the rule that \(m_l\) can take integer values from \(-l\) to \(+l\), including zero. So, \(m_l = -l, -(l-1), ..., 0, ..., (l-1), l\).
4. For \(l = 0\), the only possible value of \(m_l\) is 0, meaning there is exactly one allowed value.
5. Therefore, the number of possible \(m_l\) values for an electron in the 2s subshell is 1.