Which of the following is the strongest Bronsted base?

For the reaction $HSO_4^- + OH^- \to SO_4^{2-} + H_2O$,which statement is correct regarding the conjugate acid-base pair?

$A$ salt of sulphurous acid is called

The position of equilibrium lies to the right in each of these reactions:
$N_2H_5^+ + NH_3 \rightleftharpoons NH_4^+ + N_2H_4$
$NH_3 + HBr \rightleftharpoons NH_4^+ + Br^{-}$
$N_2H_4 + HBr \rightleftharpoons N_2H_5^+ + Br^{-}$
Based on this information,what is the order of acidic strength?

Which of the following species is an acid and also a conjugate base of another acid?

What is the conjugate acid of $HPO_4^{2-}$?