Question

Which anion is the weakest base?

• A. $C_2{H}_5{O}^{-}$
• B. $N{O}_3^{-}$
• C. $F^{-}$
• D. $C{H}_{3}CO{O}^{-}$

Answer 1

Answer: (B)

Conjugated base of a stronger acid is weak.
The corresponding acids of the given conjugated bases are as (in order of acidity)
$C_2{H}_{5}OH<C{H}_{3}COOH<HF<HN{O}_3$
$\therefore$ The order of basicity is
$C_2{H}_5{O}^{-}>C{H}_{3}COO>F^{-}>N{O}_3^{-}$
Thus, $N{O}_3^{-}$is the weakest base among the given.