Answer:
A and B are buffer solutions
Step-by-step explanation:
A buffer is the mixture of a weak base and its conjugate base or vice versa:
Formic acid, HOOH, is a weak acid and its conjugate base is HCOO⁻:
A. HCOOH+HCOO− . Is a buffer.
Acetic acid, CH₃COOH is a weak acid and its conjugate base is CH₃COO⁻:
B. CH₃COOH+CH₃COO− . Is a buffer.
Oxalic acid, H₂CO₄, is a weak acid but its conjugate base is HCO₄⁻.
C. H2CO−4+C2O2−4 . Is not a buffer
Boric acid, H₃BO₃ is a weak acid but its conjugate base is H₂BO₃⁻
D. H₃BO₃ + BO₃³⁻. Is not a buffer.