Acidic strength depends on the stability of conjugate base formed. More stable the conjugate base, stronger is the acid. The order of stability of conjugate base formed will be
H−C≡C−COO⊖>CH2=CH−COO⊖> CH3−CH2−COO⊖>CH3−CH2−O⊖
(Increase in \% character increases stability of conjugate base) ∴ Correct order of acidic strength will be
