Which of the following is an example of a chemical change? a. ice melting b. milk souring c. pounding gold into a coin d. a puddle of water evaporating

B. milk souring

Explanation:

A chemical change occurs when a react happens a compound if transformed in another one, or it's breaking down to its elements. On the other hand, a physical change occurs when there is a change in the physic state of the compound, when it passes from solid to liquid, for example.

So, ice melting is a physic change, as so a puddle of water evaporating. To pound gold into a coin, first is necessary to melting it to form the coin format, the solidify it again, so it's a physical change.

When milk sours, it's happening chemical reactions with some microorganisms, as bacteria and fungi, that transform it in compounds with the sour smell. Then, it's a chemical change.