Well the difference in electronegativity for all of those in order are, 3, 2.18, 1.98 and 1.68, so the only molecular/covalent(and it’s polar) lithium halogen within these 4 is Lithium Iodide(LiI) and the most Ionic is Lithium Fluoride(LiF).
What kind of bond is LiF?
Ionic bonding: The formation of an ionic bond between lithium and fluorine to form LiF.
Is LiF covalent?
Lithium fluroide (LiF) is mainly ionic but lithium iodide (LiI) is covalent in nature.