Which substance is most likely to form in a precipitation reaction?

A. calcium nitrate

B. copper (I) nitrate

C. iron (I) chloride

D. iron (II) sulfide

E. potassium sulfate

The answer is: D. iron (II) sulfide.

Iron (II) sulfide is black, water-insoluble solid.

Iron (Fe) is metal and sulfur (S) is nonmetal.

Iron has positive charge 2 + (cations) and sulfur negative charge 2 - (anion), which means iron lost two electrons and sulfur gain two electrons.

Balanced chemical reaction: Fe + S → FeS.

D is the answer on this one