Which of the following is not considered a chemical change?

Which of the following is not considered a chemical change?

• A. Burning of wood
• B. Tearing of paper
• C. Rusting of iron
• D. Cooking of an egg

Answer: (B)

The tearing of paper is not considered a chemical change because it involves a physical alteration of the substance, rather than a transformation of its chemical composition. When paper is torn, its physical form changes, but the molecules that make up the paper remain the same. No new substances are formed as a result of this action, which is a key characteristic of a physical change. In contrast, burning wood involves combustion that leads to the formation of ash, carbon dioxide, and other substances, signifying a chemical change. Rusting of iron is a chemical reaction with oxygen and moisture that forms iron oxide. Similarly, cooking an egg undergoes a chemical change where the proteins denature and form new structures, changing the egg from a liquid to a solid state. Each of these processes results in new substances and irreversible changes at a molecular level, which distinguishes them from the simple act of tearing paper.

The tearing of paper is not considered a chemical change because it involves a physical alteration of the substance, rather than a transformation of its chemical composition. When paper is torn, its physical form changes, but the molecules that make up the paper remain the same. No new substances are formed as a result of this action, which is a key characteristic of a physical change.

In contrast, burning wood involves combustion that leads to the formation of ash, carbon dioxide, and other substances, signifying a chemical change. Rusting of iron is a chemical reaction with oxygen and moisture that forms iron oxide. Similarly, cooking an egg undergoes a chemical change where the proteins denature and form new structures, changing the egg from a liquid to a solid state. Each of these processes results in new substances and irreversible changes at a molecular level, which distinguishes them from the simple act of tearing paper.