Question

Which statement explains how the periodic table is arranged?

A.
The periodic table is arranged by the radioactivity levels in unstable nuclei of elements.

B.
The periodic table is arranged by decreasing atomic mass.

C.
The periodic table is arranged by the outermost electrons of the elements.

D.
The periodic table is arranged by number of neutrons found within the most common isotopes.

Answer 1

C

Answer 2

i think its c to but i don't no plz explain your answer