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

The strongest Bronsted base among the following anions is:

Which are the bases of the above reaction $HCl_{(aq)} + H_2O_{(aq)} \rightleftharpoons H_3O^{+}_{(aq)} + Cl^{-}_{(aq)}$? Which base is weak?

Which among the following is the conjugate base of $HClO_4$?

Rank the following in decreasing order of basic strength:
$A. CH_3 - CH_2 - C \equiv C^-$
$B. CH_3 - CH_2 - S^-$
$C. CH_3 - CH_2 - CO_2^-$
$D. CH_3 - CH_2 - O^-$

Which of the following can act as an acid and as a base?