Souring milk is not an example of a physical change; it's actually a chemical change. In a physical change, the substance may change its form, like freezing water into ice, but it still stays the same substance. With souring milk, the bacteria break down the lactose (the sugar in milk) and produce lactic acid, making the milk taste sour. This means that the composition of the milk changes, and you can't just get back the original milk from the sour milk. So, what you see is a chemical change, not a physical one!
Why is this an example of physical change?
2. Souring milk
Yes, sour milk is formed from the milk due to bacteria.
make it sound as an 8th grader
3 answers
shorter please
Souring milk is a chemical change, not a physical one. When milk sours, bacteria break down the milk's sugar, creating lactic acid and changing its composition. You can't turn the sour milk back into fresh milk, which shows that it's a chemical change!