What is the pH range of milk?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (6.7 - 6.9)
On the pH scale 7 is neutral, below 7 acidic and above 7 basic. Fresh milk is very slightly acidic, with a pH a little below 7, because of the proteins (casein), phosphates and dissolved carbon dioxide in it. When milk turns sour, bacteria change its sugar (lactose) into lactic acid, and the pH falls further.