Question

The conjugate bases for $HC{O}_3^{-}$ and $N{H}_3$, respectively, are

• A. $H_{2}C{O}_3$ and $N{H}_4^{+}$
• B. $C{O}_3^{2-}$ and $N{H}_2^{-}$
• C. $H_{2}C{O}_3$ and $N{H}_2^{-}$
• D. $C{O}_3^{2-}$ and $N{H}_4^{+}$

Answer 1

Answer: (B)

The conjugate base differ by a proton from its respective acid.
The conjugate bases for $HC{O}_3^{-}$ and $N{H}_3$ respectively are $C{O}_3^{2-}$ and $N{H}_2^{-}$.
$\underset{\text{ Acid }}{HC{O}_3^{-}}\rightleftharpoons \underset{\text{ Conjugate base }}{C{O}_3^{2-}+H^{+}}$
$\underset{\text{ Acid }}{N{H}_3}\rightleftharpoons \underset{\text{ Conjugate base }}{N{H}_2^{-}+H^{+}}$