Answer:
Four
Step-by-step explanation:
The superscripts in an electron configuration tell us how many electrons are in a subshell.
If the electron configuration is 1s¹ 2s¹2p², the total number of electrons is
1 + 1 + 2 = 4
The atom contains four electrons.
Note: this atom is in an excited state, because the 1s and 2s subshells can each hold one more electron.
