Final answer:
HF is a weak acid because it does not completely dissociate in water to form H+ and F-, despite fluorine's high electronegativity which stabilizes the conjugate base F-.
Step-by-step explanation:
HF, or hydrogen fluoride, is a weak acid. When HF dissolves in water, it loses a proton (H+) to form its conjugate base F-. Water acts as a base by accepting this proton to form its conjugate acid H3O+. Despite having a high electronegativity which allows the fluorine atom to stabilize the negative charge in the F- ion better than carbon in a CH3- ion, HF does not completely dissociate in aqueous solutions. Therefore, it is classified as a weak acid rather than a strong acid like HCl which completely dissociates.