ANS:A - 10

The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution based on the concentration of hydrogen ions (𝐻+H+) in the solution. Each unit change in pH represents a tenfold change in the hydrogen ion concentration. Specifically, the relationship between pH and hydrogen ion concentration is given by: pH=−log⁡[𝐻+]pH=−log[H+] Therefore, if the pH value of a solution changes by one unit, it implies that the hydrogen ion concentration in the solution will change by a factor of 10. So, the correct answer is: 10