chlorine (Cl) helium (He) magnesium (Mg) silver (Ag)
I gave my students this multiple choice question: The Periodic Table of the Elements is arranged so that elements with similar characteristics are in the same column. Which element is a highly reactive metal?

Only one answer is correct among these 4 choices:
- chlorine (Cl)
- helium (He)
- magnesium (Mg)
- silver (Ag)

Could you tell me which one is correct?

magnesium (Mg)