Final answer:
Both the milk going sour and grilling a hamburger are examples of chemical changes where new substances with different properties are formed.
Step-by-step explanation:
Both changes have in common that they are chemical changes. Milk going sour involves the breakdown of sugars and denaturation of proteins, resulting in the formation of acid. Grilling a hamburger involves the Maillard reaction, where amino acids and sugars react to produce a brown color and distinctive flavor. In both cases, new substances are formed with different properties.