Identify a weak electrolyte from the following based on their dissociation nature in an aqueous medium.

In the reaction $HBr + H_2O \rightleftharpoons H_3O^{+} + Br^{-}$,the conjugate base of the weak acid is .......

The conjugate base of the strong acid in the reaction $CH_3COOH + HCl \rightleftharpoons Cl^{\Theta} + CH_3COOH_2^{\oplus}$ is:

The conjugate acid of $HPO_3^{2-}$ is

$K_{a}$ values for acids $H_{2}SO_{3}$,$HNO_{2}$,$CH_{3}COOH$ and $HCN$ are respectively $1.3 \times 10^{-2}$,$4 \times 10^{-4}$,$1.8 \times 10^{-5}$ and $4 \times 10^{-10}$. Which of the above acids produces a stronger conjugate base in aqueous solution?

$NH_4OH$ is a weak base because