Question

select all that apply
the second row of the periodic table ______.

□ includes the elements sodium, magnesium, and argon, among others.
□ has elements with two occupied energy levels.
□ ends with the noble gas neon.
□ includes eight elements.

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Explanation:

• For the option "includes the elements sodium, magnesium, and argon, among others": Sodium (Na, atomic number 11), magnesium (Mg, atomic number 12), and argon (Ar, atomic number 18) are in the third row (period 3) of the periodic table, not the second row. So this option is incorrect.
• For the option "has elements with two occupied energy levels": The period number of an element in the periodic table is equal to the number of occupied energy levels (shells) of its atoms. The second row (period 2) elements have electrons in the first (n = 1) and second (n = 2) energy levels, so they have two occupied energy levels. This option is correct.
• For the option "ends with the noble gas neon": The second row (period 2) of the periodic table starts with lithium (Li) and ends with neon (Ne), which is a noble gas. This option is correct.
• For the option "includes eight elements": The second period of the periodic table contains the elements lithium (Li), beryllium (Be), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), and neon (Ne). That's a total of eight elements. This option is correct.

Answer:

• has elements with two occupied energy levels.
• ends with the noble gas neon.
• includes eight elements.