Question

3 which elements have two electron shells? choose more than one answer. helium lithium boron calcium oxygen lead nitrogen

Explanation:

Elements in the second period of the periodic table have two electron - shells. Lithium (Li), Boron (B), Oxygen (O), and Nitrogen (N) are in the second period. Helium (He) has one electron - shell and Calcium (Ca) and Lead (Pb) have more than two electron - shells.

Answer:

B. Lithium, C. Boron, E. Oxygen, G. Nitrogen