Conjugate acid of $HPO_4^{2-}$ is

The dissociation constant values of three acids $A$,$B$ and $C$ are $1.8 \times 10^{-5}$,$1.5 \times 10^{-4}$ and $5.2 \times 10^{-8}$ respectively. The correct order of increasing basic nature of their conjugate bases is $-$

Acetic acid is a weaker acid than sulphuric acid because

Derive the equation $K_a \times K_b = K_w$.

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

Conjugate acid of $NH_2^{-}$ and $NH_3$ are respectively