A physical change can sometimes result in a color change. Which of the following situations shows this?

Question

1. Milk turns yellow when it spoils.
2. Dough becomes darker when it is baked into cake.
3. A red candy dissolves and turns water pink.
4. A match turns black when it is burned.

Answer 1

A physical change typically involves changes in state or appearance without altering the chemical composition of the substance. Let's analyze the situations:

1. Milk turns yellow when it spoils. - This is a chemical change because spoilage involves the breakdown of compounds and the formation of new substances.

2. Dough becomes darker when it is baked into cake. - This is also a chemical change due to the Maillard reaction and caramelization occurring during baking, which alters the chemical composition.

3. A red candy dissolves and turns water pink. - This represents a physical change. The candy dissolves, releasing color into the water, but the chemical structure of the candy does not change until it is fully consumed or reacts chemically.

4. A match turns black when it is burned. - This is a chemical change, as the match undergoes combustion, leading to the formation of new substances (like ash and gases).

Based on the analysis, the situation that shows a physical change resulting in a color change is 3: A red candy dissolves and turns water pink.