Acids Bases - 2 | Structure and Reactivity

When comparing the acidity of different molecules (here A and B), it is actually easier to compare the stability of their respective bases (here A' and B').

less stable base = strongest base
strongest base = weakest acid

Fluorine is more electronegative than hydrogen and has an inductive attracting effect: 
B' is more stable than A'
A' is the strongest base 
A is the weakest acid