Which of the following compounds has an electrovalent linkage?

Which type of compounds show high melting and boiling points?

Calcium and chlorine combine to form $CaCl_2$,but they do not form $CaCl$. This is because:

Electrovalent bond formation depends on

For ionic solids,choose the correct option using $T$ (True) or $F$ (False) for the following statements:
$(1)$ They have very high melting and boiling points.
$(2)$ They are electrolytes.
$(3)$ They possess directional bond characteristics.
$(4)$ They can have isomorphic types of structures.

Which among the following compounds shows the highest lattice energy?