Which element has?
(a) Two shells, both of which are completely filled with electrons?
(b) The electronic configuration 2, 8, 2?
(c) A total of three shells, with four electrons in its valence shell?
(d) A total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?

(a) Neon contains two full shells.

(b) The electronic configuration of magnesium is 2, 8, 2.

(d) Boron has three electrons in its valence shell and a total of two shells.

(e) The second shell of carbon has twice as many electrons as the first shell.