Here's why:

* pH scale: The pH scale measures the acidity or alkalinity of a substance. It ranges from 0 to 14.

* Acidic: Substances with a pH below 7 are acidic.

* Neutral: A pH of 7 is considered neutral (like pure water).

* Alkaline/Basic: Substances with a pH above 7 are alkaline or basic.

Examples of substances with a pH of 9:

* Baking soda solution: A common household ingredient used for cleaning and baking.

* Some soaps: The pH of soap can vary, but some types have a pH of 9.

Keep in mind that a pH of 9 is still relatively mild compared to stronger alkaline solutions.