The ionic character of H-X is highest in
The ionic charcter is expected to increase as the electronegativity of the halogen increases. Thus due to the highest electronegativity difference in H and F, the H-F bond should be most ionic. But H-I bond being the weakest gives the hydrogen readily. HI is also the strongest acid because of its least bond dissociation energy.The ionic charcter thus follows the order HI>HBr>HCl>HF.