Which is an example of a physical change?
A. rusting iron
B. toasting bread
C. burning leaves
D. bolling alcohol
B. toasting bread
A physical change refers to a change that does not result in the formation of a new substance. Out of the options provided, an example of a physical change is B. toasting bread.
To determine which of the options is an example of a physical change, we need to understand the characteristics of physical changes.
A physical change is a type of change in which the substance involved undergoes a transformation that does not alter its chemical composition. In other words, the identity of the substance remains the same even though its physical properties might have changed.
Let's analyze each option to identify the physical change:
A. Rusting iron: Rusting is actually a chemical change. The iron reacts with oxygen in the presence of water to form a new compound called iron oxide (rust). Since a new substance is formed, rusting is not a physical change.
B. Toasting bread: Toasting bread involves heating the bread, causing its color and texture to change. However, the chemical composition of the bread remains the same. The process of toasting bread is a physical change.
C. Burning leaves: Burning is a chemical change. When leaves burn, they undergo a chemical reaction, transforming the organic material in the leaves into ash, smoke, and gases. Therefore, burning leaves is not a physical change.
D. Boiling alcohol: Boiling is a physical change. When alcohol is heated, it changes from a liquid to a vapor state. The chemical composition of alcohol remains the same; only its physical state changes. Therefore, boiling alcohol is a physical change.
Based on the explanations above, the correct answer is (D) boiling alcohol, as it is an example of a physical change.