The conjugate base of $HPO_4^{2-}$ is .....

If the $pK_b$ of the fluoride ion $(F^-)$ at $25^{\circ}C$ is $10$,what is the ionization constant $(K_a)$ of hydrofluoric acid $(HF)$ at the same temperature?

The species among the following,which can act as an acid and a base is

$A$ substance containing hydrogen and releasing $H^{+}$ in aqueous medium is an acid. Identify the theory suggesting this concept from the following.

The dissociation of $H_3PO_4$ occurs in how many stages?

$A$ tribasic acid is: