The polarizability difference between oxygen and fluorine is not enough to have a stong effect on basicity because these two atoms are in the same row of the periodic table. Oxygen is less electronegative than fluorine, and therefore less resistant to sharing an electron pair with a proton. Resonance is not a factor here. Polarizability and electronegativity are not factors here, as each base bears the charge on a carbon atom. This leaves the inductive effect.
Chlorine is more electronegative than hydrogen.
Thus CHCl 3 is a stronger acid than CH 4 . 20. Protonation of acetate ion results in a loss of this stabilziation, whereas protonation of trifluoroethoxide does not. Thus protonation of acetate ion is thermodynamically less favorable than protonation of trifluoroethoxide. Recall that resonance is more influential than the inductive effect, so the CF 3 group of CF 3 CH 2 OH was not considered. This CF 3 group makes CF 3 CH 2 OH more acidic than CH 3 CH 2 OH, but does not outweigh the resonance effect in acetate ion.