Which among the following pairs is not an acidic buffer?

Step-by-step solution

The buffer solution is that solution which resist any change in its pH upon addition of small amount of acid or base to it. Acid buffer has acidic pH and is prepared by mixing a weak acid and its salt with a strong base. Here, HClO 4 is a strong acid as because the chlorine atom is in its highest oxidation state. So that's why this mixture is not a acidic buffer in nature