Which set of quantum numbers could correctly describe a subshell containing valence electrons in a Se atom?

Question

Which set of quantum numbers could correctly describe a subshell containing valence electrons in a Se atom?

I. n=4, l=0

II. n=4, l=1

III. n=3, l=2

Answer 1

Looking at the periodic table we see that Se (selenium) is atomic number 34, and is in period 4 and group 16.

The valence electrons would therefore be in the 4p subshell and there would be 4 such valence electrons. So, the valence electrons would have the configuration of 4p. For this configuration, n = 4 and l = 1 so it would be choice (II).