What will be the conjugate acid-base pair in the reaction $HCl_{(aq)} + H_2O_{(aq)} \rightleftharpoons H_3O^{+}_{(aq)} + Cl^{-}_{(aq)}$?

Cis-butene dioic acid $\overset{K_{a_1}(-H^+)}{\longleftrightarrow} X_1^- \overset{K_{a_2}(-H^+)}{\longleftrightarrow} X_2^{2-}$
Trans-butene dioic acid $\overset{K'_{a_1}(-H^+)}{\longleftrightarrow} Y_1^- \overset{K'_{a_2}(-H^+)}{\longleftrightarrow} Y_2^{2-}$
The incorrect statement regarding the above information is:

Which of the following is not a conjugate acid-base pair?

The first ionization constants ($pK_a$ values) for the following dicarboxylic acids are given:
Oxalic acid: $pK_1$
Malonic acid: $pK_2$
Heptanedioic acid: $pK_3$
Which of the following represents the incorrect order of their $pK_a$ values?

Match the following species with their respective conjugate acids:

Species	Conjugate acid
$ (a) NH_{3} $	$ (i) H_{2}CO_{3} $
$ (b) HCO_{3}^{-} $	$ (ii) H_{3}O^{+} $
$ (c) H_{2}O $	$ (iii) NH_{4}^{+} $
$ (d) HSO_{4}^{-} $	$ (iv) H_{2}SO_{4} $

Acidity of $BF_3$ can be explained on which of the following concepts?