H2CO3 and Na2CO3
H3PO4 and Na3PO4
HClO4 and NaClO4
CH3COOH and CH3COONa
An acidic buffer includes a weak acid and its salt with a strong base. HClO4 and NaClO4 contains a strong acid (HClO4) and its salt with a strong base (NaOH). HClO4 and NaClO4 is not an acidic buffer. Hence, option C is correct.