Final answer:
The strength of an acid or base is measured on the pH scale, which is a numeric scale that ranges from 0 to 14. Acidity increases with decreasing pH values, and basicity increases with increasing pH values.
Step-by-step explanation:
The strength of an acid or base is measured on a scale called the pH scale. This is a numeric scale that ranges from 0 to 14. In this range, a substance with a pH less than 7 is considered acidic, whereas a substance with a pH greater than 7 is considered basic. A pH of 7 is considered neutral - which is the pH of pure water at 25 degrees Celsius. This pH scale is logarithmic, which means each pH value is 10 times more or less acidic or basic than the one next to it. For example, lemon juice, which has a pH of 2, is 10 times more acidic than tomatoes with a pH of 3.
Learn more about pH scale