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

Question

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

a)all of these

b)HS^- and H2S

c)None of these

d)H2PO4^- and HPO4^2-

e)NH3 and NH4^+

Answer 1

Then only difference between an acid and base in a conjugate pair is H⁺ ion. Specifically, the acid contains the H⁺ and after donation converts to its conjugate base. Likewise, when a prospective base gains an H⁺ ion, it converts into its conjugate acid.

So, in choice b) HS^- is the conjugate base of H₂S. In choice d) H₂PO₄^- is the conjugate acid of HPO₄^2- and in choice e) NH₃ is the conjugate base of NH₄⁺.

It appears the answer is a) all of these. Hope this helps.