8 Which elements have the most similar chemical properties?

(1) Si, As, and Te (3) Mg, Sr, and Ba

(2) N2, O2, and F2 (4) Ca, Cs, and Cu

Silicon, Arsenic, and Tellurium all sit on the metal/nonmetal boundary

Magnesium, Strontium, and Barium are in the same group (Group 2)

Nitrogen, Oxygen, and Flourine are all non-metals in the same period

Calcium, Caesium, and Copper start with the same letter

So (3) Mg, Sr and Ba is the correct answer

Elements in the same group have simimlar chemical properties due to their identical valence electron shells. Since it is mainly the valence shell involved in chemical reactions, chemical properties tend to depend heavily on valence shell electron configuration. That is why the elements in choice 3) have the most similar chemical properties.