Question

Which one of the following species cannot act as both Bronsted acid and base?

• A. $H_{2}O$
• B. $HC{O}_3{}^{-}$
• C. $HS{O}_4{}^{-}$
• D. $N{H}_2{}^{-}$
• E. $N{H}_3$

Answer 1

Answer: (D)

$N{H}_2{}^{-}$

${N{H}_2}^{-}$, Because it does not have any conjugate acid nor any conjugate base.

Others have the same like:

Species C.A. C.B.

$H_{2}O$ $H_3{O}^{+}$ $O{H}^{-}$

${HC{O}_3}^{-}$ $H_{2}C{O}_3$ ${C{O}_3}^{2-}$

${HS{O}_4}^{-}$ $H_{2}S{O}_4$ ${S{O}_4}^{2-}$

$N{H}_3$ ${N{H}_4}^{+}$ ${N{H}_2}^{-}$