In the reaction:
\[ \text{H}_2\text{Se} + \text{H}_2\text{O} \rightarrow \text{SeH}^- + \text{H}_3\text{O}^+ \]
we can identify the acid, base, conjugate acid, and conjugate base as follows:
- Acid: \(\text{H}_2\text{Se}\) (it donates a proton)
- Base: \(\text{H}_2\text{O}\) (it accepts a proton)
- Conjugate Acid: \(\text{H}_3\text{O}^+\) (it is formed when water accepts a proton)
- Conjugate Base: \(\text{SeH}^-\) (it is formed when \(\text{H}_2\text{Se}\) donates a proton)
Thus, the correct identification is:
- Acid: H2Se
- Base: H2O
- Conjugate Acid: H3O+
- Conjugate Base: SeH−
This matches with the third option in your responses.