What range of pH values indicates an acid solution?

An acid solution is characterized by a pH value that is less than 7. The pH scale ranges from 0 to 14, where values below 7 indicate acidity, with 0 being the most acidic. This range reflects the concentration of hydrogen ions in the solution, where higher concentrations correspond to lower pH values, indicating stronger acids.

When a solution has a pH value of under 7, it signifies an increased level of hydrogen ions, which is a key indicator of acidity. Therefore, the correct answer encompasses all values from just under 7 down to 0, confirming that any pH measurement in that range denotes an acidic condition.

Other ranges mentioned, such as 0 to 5, while technically indicating acid solutions, do not fully encompass the entire spectrum of acidity on the pH scale. The ranges of 6 to 8 and 7 to 10 fall within neutral and basic categories, which do not apply to acidic conditions. Thus, recognizing the full range from under 7 down to 0 is crucial for understanding the properties of acid solutions.