Which of these pairs of elements would be most
likely to form an ionic compound?
Select one:
O A. Cl and I
o B. Cl and Mg
O C. Al and Mg
o D. Al and K.
o E. Cand s

The correct answer is  B) Cl and Mg

Explanation:

An ionic bond is produced by the union of a cation and an anion. In this case, Mg would be the cation and Cl the anion. They will form the compound Magnesium Chloride (MgCl2):

Mg + Cl2 > MgCl2

Mg belongs to group 2 of the periodic table, that is, it has two valence electrons. In the case of Cl, it is in group 7 and has seven valence electrons (requires one electron to complete the octet).