Which of the following properties describes a substance with a high pKa?

A high pKa value indicates that a substance is a weak acid. The pKa is a logarithmic measure of the acidity of a substance; the higher the pKa, the weaker the acid. This is because pKa is derived from the acid dissociation constant (Ka). A higher pKa means a lower Ka, which corresponds to a tendency of the acid to resist dissociation in solution.

As a weak acid, a substance with a high pKa does not release a significant amount of protons (H+) compared to strong acids, thus it will have a stronger basic character. This means that it is more likely to accept protons and act as a base. Therefore, the property of being a weak acid directly correlates with having a higher pKa, confirming that such substances are indeed more basic compared to stronger acids.

In contrast, strong acids have lower pKa values because they are fully dissociated in solution, whereas weak acids are only partially dissociated.