Answer:
b. At the equivalence point of the titration of a weak base with strong acid.
Explanation:
Equivalence point is the point in a chemical reaction at which chemically equivalent quantities of acid and base have been mixed.
From the diagram below;
If we look at the titration between a strong base and a weak acid., the titration curve reflects that the strength of the corresponding acid and base, showing the pH change during titration.
The titration curve demonstrating the pH change during the titration of the strong base with a weak acid shows that;
At the beginning, the pH changes very slowly and gradually from a strong acidic medium. This indicates the formation of a buffer system of a weak acidic medium as the titration approaches the equivalence point.
At the equivalence point of the titration of a weak base with strong acid, we can see clearly that the weak acid only is present.
After the equivalence point and beyond, the titration curve is Basic.