As we move down the group in periodic table, the bond’s covalent character increases, which invariably is related to the decrease in difference between the electronegativities of the bonding atoms, which means decrease in polarity of the molecule. Also as the size of anion increases, the tendency to polarise cation increases. Covalent compounds are insoluble in water. AgF will be most ionic compound. Therefore, the order of solubility of halides of silver will be:
Agl < AgBr < AgCl < AgF
