Question

Strongest conjugate base is

• A. $ClO ^{-}$
• B. $ClO _{2}^{-}$
• C. $ClO _{3}{ }^{-}$
• D. $ClO _{4}{ }^{-}$

Answer 1

Answer: (A)

If acid is weak, its conjugate base is strong. Greater the oxidation number of $Cl$, stronger the acid and thus, weaker the conjugate base.

Oxidation number of $Cl$ and acid strength increases
$\xleftarrow{ClO ^{-} ClO _{2}^{-} ClO _{3}^{-} ClO _{4}^{-}}$
Conjugate base strength increases.
Hence, $ClO ^{-}$is the strongest base.