Milk tastes sour when kept in the open for sometime due to the formation of
(1) lactic acid
(2) citric acid
(3) acetic acid
(4) carbonic acid
Answer: (1) Like many other things, Milk contains bacteria; Milk also naturally contains a kind of sugar known as “lactose.” The bacteria that live in Milk get energy from this special sugar and use it to reproduce to make even more bacteria. When the bacteria use the lactose sugars to reproduce, they change it from “lactose sugar” into “lactic acid,” which tastes sour.
