alleryThe four quantum numbers describing an electron in an atom are:
A$n, l, m_l, m_s$
B$n, l, m_l, m_l$
C$n, p, d, f$
D$n, l, m, s$
Answer & Solution
Correct answer: A. $n, l, m_l, m_s$
**Principal $n$** sets the shell and energy. **Azimuthal $l$** sets the subshell shape (s, p, d, f). **Magnetic $m_l$** sets the orbital's orientation in space. **Spin $m_s$** picks $+\tfrac{1}{2}$ or $-\tfrac{1}{2}$.
First three come from the Schrödinger equation
the spin comes from electron's intrinsic angular momentum. Option D lists subshell labels (s, p, d, f), not quantum numbers.
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