Which of the following is not a conjugate acid-base pair? A. H3O+/OH−
B. NH4+/NH3
C. C2H3O−2/HC2H3O2
D. H2SO3/HSO−3
E. All of the above are conjugate acid base pairs.

A. H3O+/OH−

Explanation:

A conjugate acid-base pair are a pair of molecules that differ in 1 H⁺

A. The conjugate pair of H₃O⁺ = H₂O not OH⁻

B. The conjugate pair of NH₄⁺ is NH₃

C. The conjugate pair of C₂H₃O₂⁻ is HC₂H₃O₂

D. The conjugate pair of H₂SO₃ is HSO₃⁻

That means right option, that is not a conjugate acid-base pair, is:

the formula would be mgso4

mgso[subscript]4

i think its 5049.

i hope this !