Here's why:

* pH Scale: The pH scale ranges from 0 to 14.

* Values below 7 are acidic.

* Values above 7 are basic (also called alkaline).

* A pH of 7 is neutral.

* Ammonia's Properties: Ammonia (NH₃) is a weak base. In solution, it accepts protons (H⁺) to form ammonium ions (NH₄⁺), raising the pH.

Since a pH of 11.5 is significantly above 7, it falls within the basic range.