Here's why:

* Hydrochloric acid (HCl) is a strong acid. This means it completely ionizes in water, releasing hydrogen ions (H+).

* Dilution simply means adding more water. While it reduces the concentration of H+ ions, it doesn't change the fact that HCl is an acid.

* Acids are substances that donate H+ ions in solution.

Even a diluted solution of hydrochloric acid will still have a higher concentration of H+ ions than pure water, making it acidic.