The conjugate bases of Bronsted acids H₂O and HF are respectively:

1. H₃O⁺ and H₂F⁺, respectively.

2. OH^– and H₂F⁺, respectively.

3. H₃O⁺ and F^–, respectively.

4. OH^– and F^–, respectively.

Which of the following cannot act both as a Bronsted acid and as a Bronsted base?

1. \(\mathrm{H C O_{3}^{-}}\)

2. \(\mathrm{NH_3}\)

3. HCl

4. \(\mathrm{H S O_{4}^{-}}\)