Why does anhydrous aluminium chloride have lower melting point than anhydrous aluminium fluoride?

Explanation:

Molecule of aluminium fluoride is more polar than molecule of aluminium chloride . It is so because fluorine is more electronegative than chlorine . On Pauling scale , the electronegativity of fluorine is 3.98 whereas that of chlorine is 3.16 . Hence in aluminium fluoride , there is stronger inter molecular bonding because of  more polar nature of molecules .  In aluminium chloride  , there is weaker  inter molecular bonding because of  comparatively  polar nature of molecules . Hence melting point of anhydrous aluminium fluoride is higher than that of anhydrous aluminium chloride .

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements