Fresh milk has a pH of 6. What is the change in pH value when milk turns into curd?

pH decreases

The correct answer is option 2. pH decreases.

When milk turns into curd, the pH decreases. The change in pH is typically associated with the process of fermentation, where bacteria convert lactose (milk sugar) into lactic acid. This increase in acidity leads to a decrease in pH. Curd or yogurt generally has a lower pH compared to fresh milk due to the presence of lactic acid.