Question

which element behaves the most like calcium and why?
○ k because it is in the same period and only has one less valence electron.
○ ba because it is in the same group and has same number of valence electrons.
○ br because it is in the same period and has more valance electrons.
○ sc because it is in the same period and has one more valence electron.

Explanation:

Elements in the same group have similar chemical properties due to the same number of valence - electrons. Calcium and barium are in the same group.

Answer:

Ba, because it is in the same group and has same number of valence electrons.