How many of the following are diprotic acids? Citric acid,Chromic acid,Oxalic acid,Pyrosulfuric acid,Sulfurous acid

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

The dissociation constants $(K_a)$ of four acids are given below. Which of these is the strongest acid?

The nitrating mixture contains concentrated $H_2SO_4$ and concentrated $HNO_3$. In this mixture,$HNO_3$ acts as a:

The conjugate acid of a strong base is a

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 $-$