An electron's quantum number falls under which structure classification o macroscopic o subatomic atomic omicroscopic o none of the above

O subatomic atomic

Explanation:

Each orbitals of an atom and electrons accommodated are described by a set of quantum numbers. These numbers gives the position of an orbital with respect to the nucleus, the shape of the orbital, its spatial orientation and the spin of the electron in the orbital.

The quantum numbers can be used to write proper sub-level notation of an atom.

it's c. elements are placed in rows based on how may valencies electrons have.

thats a little if u want the answer just look it up on google thats what i do haha : )