Question

Choose the most acidic substance in the group.

Answer 1

It would be lemon juice since it has the lowest pH

Answer 2

Answer: 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 $H^+$ ions. Acids have pH raging from 1 to 6.9

$HX\rightarrow H^++X^-$

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

$pH=-\log [H^+]$

Thus as pH and $H^+$ are inversely related, a solution having lower pH will have more amount of $H^+$ 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.