Final answer:
The pH scale measures the acidity or basicity of a substance.
Step-by-step explanation:
The pH scale measures acidity or basicity of a substance. It is a scale ranging from 0 to 14, with 7 being neutral. A pH value less than 7 indicates acidity, while a pH value greater than 7 indicates basicity. For example, lemon juice has a pH of around 2, making it acidic, while baking soda has a pH of around 9, making it basic.
Learn more about pH scale measurement