A neutral atom has two electrons with n = 1, eight electrons with n = 2, eight electrons with n = 3, and one electron with n = 4. It has no other electrons. What is the atomic number of this element?

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium