Among the following,which one has the highest cation to anion size ratio?

Which one of the following compounds is ionic?

Which type of compounds show high melting and boiling points?

The correct solubility order is:

Element $x$ is strongly electropositive and $y$ is strongly electronegative. Both elements are univalent. The compound formed from their combination will be:

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