Choose the most acidic substance in the group. lemon juice, ph = 2.25 orange juice, ph = 3.75 milk, ph = 6.6 seawater, ph = 8

lemon juice, pH = 2.25

Explanation:

pH is the measure of acidity or alkalinity of a solution.

Acids are the substances which dissociate in water to give ions. Acids have pH raging from 1 to 6.9

pH is calculated by taking negative logarithm of hydrogen ion concentration.

Thus as pH and are inversely related, a solution having lower pH will have more amount of concentration and thus would be more acidic.

Thus lemon juice with lowest pH of 2.25 will have highest concentration of hydrogen ions and is most acidic.