pH value 1 represents a solution with the lowest OH⁻ion concentration.
Step-by-step explanation:
pH is given by the expression as the negative logarithm to the base 10 of the concentration of hydrogen ions.
pH = -log₁₀[H⁺]
If the pH is lower than 7, pH < 7 then it is acidic
If the pH = 7, then it is neutral
If the pH > 7, then it is basic
If pH is 1 then the solution is showing mostly acidic character,which is least basic in its character.
So if the pH is 1, which is most acidic and least basic solution that is lowest OH⁻ ion concentration.