Question

The conjugate bases for $HCO^{-}_3$ and $NH_3$, respectively, are

• A. $H_2CO_3$ and $NH^{+}_4$
• B. $CO^{2-}_3$ and $NH^{-}_2$
• C. $H_2CO_3$ and $NH^{-}_2$
• D. $CO^{2-}_3$ and $NH^{+}_4$

Answer 1

Answer: (B)

The conjugate base differ by a proton from its respective acid.
The conjugate bases for $HCO^{-}_3$ and $NH_3$ respectively are $CO^{2-}_3$ and $NH^{-}_2$.
$\underset{\text { Acid }}{ HCO _{3}^{-}} \rightleftharpoons \underset{\text { Conjugate base }}{ CO _{3}^{2-}+ H ^{+}}$
$\underset{\text { Acid }}{ NH _{3}} \rightleftharpoons \underset{\text { Conjugate base }}{ NH _{2}^{-}+ H ^{+}}$