1. The problem asks which acid among OHNO2, CH3COOH, OHSO4, and HF has the strongest conjugate base. 2. The strength of a conjugate base is inversely related to the strength of its acid: the weaker the acid, the stronger its conjugate base. 3. We compare the acid strengths: - CH3COOH (acetic acid) is a weak acid. - HF (hydrofluoric acid) is a weak acid but stronger than acetic acid. - HNO2 (nitrous acid, assuming OHNO2 is a typo for HNO2) is a weak acid stronger than acetic acid. - H2SO4 (assuming OHSO4 is sulfuric acid) is a strong acid. 4. Since H2SO4 is the strongest acid, its conjugate base (HSO4-) is the weakest base. 5. HF is stronger than acetic acid, so its conjugate base (F-) is weaker than acetate (CH3COO-). 6. Therefore, the weakest acid is CH3COOH, so its conjugate base CH3COO- is the strongest base among the options. 7. Final answer: CH3COOH has the strongest conjugate base.