ANS:A - pH value

The pH value is a measure of the acidity or alkalinity of a solution. It quantifies the concentration of hydrogen ions (H+) present in the solution. The pH scale ranges from 0 to 14, where:

• pH values less than 7 indicate acidity, with lower values representing stronger acidity.
• A pH of 7 indicates neutrality, where the concentration of H+ ions is equal to the concentration of hydroxide ions (OH−).
• pH values greater than 7 indicate alkalinity, with higher values representing stronger alkalinity.

Mathematically, pH is defined as the negative logarithm (base 10) of the hydrogen ion concentration: pH=−log10​[H+] So, a lower pH value corresponds to a higher concentration of hydrogen ions, indicating a more acidic solution, while a higher pH value corresponds to a lower concentration of hydrogen ions, indicating a more alkaline solution.