Answer: I and IV
Explanation: Ionic compounds are formed by transfer of electrons from an element to another element.
In the formation of ionic compounds usually metals lose electrons to form cations and nonmetals accept electrons to form anions. The cations and anions are held by strong coloumbic forces.
As ionic compounds are polar, they easily dissolve in water which is also a polar molecule.
Ionic compounds exist as crystalline solids due to a regular arrangement of atoms in the crystal lattice.
