Out of the following,which compound will have electrovalent bonding?

Which type of bonding exists in $Li_2O$ and $CaF_2$ respectively?

The ionic bonds $X^{+}Y^{-}$ are formed when
$I$. electron affinity of $Y$ is high
$II$. ionization energy of $X$ is low
$III$. lattice energy of $XY$ is high
$IV$. lattice energy of $XY$ is low
Choose the correct code.

An ionizing solvent has

Which pair of atoms forms the strongest ionic bond?

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.