Question

The correct set of four quantum numbers for outermost electron of potassium $ (Z=19) $ is

• A. $ 4,\,1,\,0,\,\frac{1}{2} $
• B. $ 3,\,1,\,0,\,\frac{1}{2} $
• C. $ 4,\,0,\,0,\,\frac{1}{2} $
• D. $ 3,\,0,\,0,\,\frac{1}{2} $

Answer 1

Answer: (C)

$K(19): 1 s^{2}, 2 s^{2}\, 2 p^{6}, 3 s^{2}\, 3 p^{6}, 4 s^{1}$
$4 s^{1}$ is the valence electron in potassium, hence the correct set of four quantum numbers for outermost electron is $4,0,0, \frac{1}{2}$.