Final answer:
The evidence for a chemical change is the formation of an insoluble substance after combining two solutions, as this indicates that a chemical reaction has occurred and new substances with different properties have been formed.
The correct answer is D.
Step-by-step explanation:
The student has asked a question focusing on identifying evidence of a chemical change. Among the options provided, the one that indicates a chemical change is D) an insoluble substance forms after combining two solutions.
In chemistry, a chemical change occurs when substances combine to form a new substance with different properties, and this process often involves the formation of a precipitate if two soluble solutions are mixed to form an insoluble substance. This is contrasted with physical changes, which include changes like a substance melting (A), which does not involve making or breaking chemical bonds.
For example, when sodium chloride (NaCl) is mixed with silver nitrate (AgNO3), a chemical reaction takes place, forming insoluble silver chloride (AgCl) as a precipitate. This demonstrates a chemical change as new chemical bonds have been formed.