How is the strength of acid or base in water measured?

The strength of an acid or base in water is measured using the pH scale, which ranges from 0 to 14. This scale quantifies the acidity or basicity of a solution based on the concentration of hydrogen ions (H⁺) present. A pH of 7 is considered neutral, indicating a balanced concentration of hydrogen and hydroxide ions. Values below 7 represent acidic solutions, with lower numbers indicating stronger acids, while values above 7 indicate basic or alkaline solutions, with higher numbers indicating stronger bases.

The other options do not accurately reflect how acid or base strength is measured. Milliliters are a unit of volume, not a measure of strength or concentration. A conductivity meter measures the ability of a solution to conduct electricity, which can provide indirect information regarding ion concentration but does not measure pH directly. Temperature range, while it can affect pH readings, is not a method for measuring the strength of an acid or base. Thus, the scale of 0 to 14 is the definitive method for assessing the strength of acids and bases in aqueous solutions.