Answer: [tex]CaO[/tex], [tex]CaF_2[/tex], or [tex]CaCl_2[/tex]
Explanation:- For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here calcium metal is having an oxidation state of +2, thus the anions must bear a negative charge to form neutral ionic compound.
Thus the possibilities are:
[tex]Ca^{2+}+O^{2-}\rightarrow CaO[/tex]
[tex]Ca^{2+}+P^{3-}\rightarrow Ca_3P_2[/tex]
[tex]Ca^{2+}+Cl^{-}\rightarrow CaCl_2[/tex]
[tex]Ca^{2+}+F^{-}\rightarrow CaF_2[/tex]