Question

Which of the following is a conjugate base?

• A. $O^{2-}$
• B. $C^{2-}$
• C. $T{e}^{2-}$
• D. $S{e}^{2-}$

Answer 1

Answer: (A)

$O^{2-}$

Adding one $H^{+}$ to anything gives you its conjugate acid.

Removing one $H^{+}$ gives you its conjugate base.

Hence the conjugate acid of oxide ion $\left(O^{2-}\right)$ is Hydroxide ion $O{H}^{-}$.