Answer:
HCO₂/H₂O is not the acid-base conjugate pair.
Step-by-step explanation:
Acid and conjugate base pairs differ by an H+ ion.
Neither HCO₂ nor H₂O has lost or gained protons.
The conjugate acid of H₂O is H₃O⁺
The conjugate base of HCO₃⁻ is CO₃²⁻
[A conjugate acid has one more H⁺ than its base]