In the reaction where $HNO_3$ acts as a base,which of the following acts as the strongest acid?

Which of the following is a conjugate acid-base pair?

Which of the following is an amphoteric substance?

Match the following acids in List-$I$ with their respective acid dissociation constants $(K_a)$ in List-$II$:

List-$I$ (Acid)	List-$II$ $(K_a)$
$A$. Phenol	$I$. $1 \times 10^{-13}$
$B$. Benzoic acid	$II$. $3.0 \times 10^{-8}$
$C$. $HClO$	$III$. $1.0 \times 10^{-10}$
$D$. $CH_3COOH$	$IV$. $6.5 \times 10^{-5}$
	$V$. $1.75 \times 10^{-5}$

The correct match is:

Considering the following reactions,which pair of reactions shows that water has basic properties?
$(i) \ CO_2 + H_2O \rightleftharpoons H_2CO_3$
$(ii) \ NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^-$
$(iii) \ HCl + H_2O \rightleftharpoons Cl^- + H_3O^+$

The conjugate base of sulphuric acid is