The number of dissociable protons in "orthophosphoric acid" is

Give the conjugate acid and conjugate base of the following:
$(i)$ $(CH_3)_2NH$
$(ii)$ $HPO_4^{2-}$
$(iii)$ $HS^{-}$

Given the following $K_a$ values,determine which species is the strongest base: $HSO_4^- = 1.2 \times 10^{-2}$,$H_2PO_4^- = 6.3 \times 10^{-8}$,$HCO_3^- = 4.7 \times 10^{-11}$.

For the reaction $NH_4^+ + S^{2-} \rightleftharpoons NH_3 + HS^-$,identify the nature of $NH_3$ and $HS^-$ in the context of the Brønsted-Lowry theory.

Aqueous ammonia is used instead of aqueous $NaOH$ solution to precipitate $Al^{3+}$ ions as $Al(OH)_3$ because .................

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: