Answer
$O^{2-}$ and $H_2O$ aren't a conjugate acid-base pair.
Work Step by Step
- Fast method:
A conjugate acid-base pair has exactly one $H^+$ as a difference. So, this isn't a valid pair.
- Other method:
1. Identify the base:
- $O^{2-}$
** $H_2O$ can act as a base, too, but $O^{2-}$ is stronger and has a lower quantity of hydrogens.
2. Add a $H^+$ to it:
- $OH^-$
Compare it to the other substance:
$OH^- \ne H_2O$
- So, this isn't a conjugate acid-base pair.
